The Council on American-Islamic Relations (CAIR) - the largest Muslim advocacy group in the US, calls the shooting "horrifying".

In a statement published online, CAIR says that school children were inside studying when the attack unfolded.

"We strongly condemn this horrifying act of violence at the Islamic Center of San Diego," CAIR-San Diego Executive Director Tazheen Nizam says.

"Our thoughts are with everyone impacted by this attack. No one should ever fear for their safety while attending prayers or studying at an elementary school.

"We are working to learn more about this incident and we encourage everyone to keep this community in your prayers.”

Imam Taha Hassane of the Islamic Center ends the press conference saying the centre is "a house of worship, not a battlefield".

"Muslims and non-Muslims alike have always been welcome at the Islamic Center," he says.

He adds that the Muslim community is mourning and requested the media to stop sharing pictures of victims, asking them to respect the families of the victims.

He then urges people to spread a culture of love and tolerance.

San Diego Police Chief Scott Wahl says a suicidal person is not going to take three weapons.

He's referring to the conversations police had with the mother of one of the suspects, who had discovered her weapons and vehicle were missing after her son left with a companion dressed in camouflage. She was initially concerned her son was suicidal.

Wahl says he wants to clarify that "there was no specific threat, especially no specific threat to the Islamic centre".

"It was general hate speech that covered a wide gamut," he says of the letter that the mother of one of the suspects found.

There was no specific threat to any religious facility or any other location, he says, adding that the letter contained "generalised hate rhetoric and hate speech".

San Diego Police Chief Scott Wahl says the suspect's mother found a note left behind.

Wahl would not give further details on what was in the note.

He adds that while the mother was on the phone with police that morning, she began putting together a bigger picture, noting her missing weapons and car.

Wahl says they believe the security guard who was killed was able to help minimise the threat at the mosque.

"Undoubtedly, he saved lives today," the police chief says, adding that he "was heroic".

The San Diego police chief is now taking questions from the media.

Wahl says that officers are only five hours into their work, and they are actively investigating this shooting as a hate crime.

He says they are investigating what "hate speech", or hate words, were conveyed throughout the incident.

"There was definitely hate rhetoric that was involved," he says.

San Diego Mayor Todd Gloria tells the briefing that no one in the city should "live in fear" because of their faith.

"Hate has no home in San Diego, Islamaphobia has no home in San Diego," he says.

The mayor adds that there will be extra police guarding all houses of worship in San Diego.

FBI Special Agent in Charge Mark Remily is now speaking.

He says agents are processing evidence and working closely with local law enforcement.

He asks the public to send photos, videos or any evidence to the FBI as they continue their investigation.

Officers entered the Islamic Center to look for suspects, Wahl says, using active shooter protocols they had trained for.

As they searched room by room, police began receiving calls of shots being fired from a vehicle at a landscaper a few blocks away.

The landscaper appears OK, but he may have been shot in the helmet, deflecting the bullet. Police had said earlier that he was uninjured, and the police chief says this last point has not yet been confirmed.

Wahl says another call reported two suspects in a vehicle with gunshot wounds, and when police got there they found them deceased.

San Diego Police Chief Scott Wahl says police were already searching for the suspects when they got a call at 11.43 local time that there was an active shooter at the Islamic Center.

Wahl adds officers were communicating with the mother of one of the suspects just a few blocks away when the shooting was reported.

When officers arrived they came across three deceased individuals, one of which was a security guard at the center.

Wahl says the woman told police her son was with a companion and they were dressed in camo.

The police chief says that is "not consistent" with what they typically see of someone who is suicidal.

Officers were sent to a shopping mall near where the vehicle had been spotted, Wahl says. One of the individuals was linked to a local high school, so officers were sent there too, he adds.

San Diego Police Chief Scott Wahl starts the briefing by offering his condolences to the Muslim community and the families of the deceased, and calls the shooting an "absolute worst nightmare".

Wahl says that about 9:42 local time, police received a call about "a runaway juvenile".

Officials spoke to a mother, who he says had pieced together bits of information over a period of time. That info elevated the threat level, he adds.

She believed her son was suicidal and shared information that "several of her weapons were missing".

Her vehicle was also missing.

We're expecting another update from the San Diego Police Department shortly. You can watch it live at the top of this page.

Stay with us as we bring you the latest developments.

Image source, Los Angeles Times via Getty Images

The Al Rashid School is located on the campus of the Islamic Center and offers weekend classes in "Arabic language, Islamic studies and Qur'an for young Muslims", according to its website.

Students who attend are aged five and up, with classes held every Saturday for both Arabic speaking and non-Arabic speaking families.

The center also offers a variety of family and youth programs, and it is busy with educational, religious and community gatherings.

We reported earlier aerial footage of children being evacuated through a parking lot of the Islamic Center, with nearby schools also placed on lockdown.

Officials have given an update after a deadly shooting at the Islamic Center of San Diego in Clairemont. Here's what we know about the incident:

• Five people have died, including three adult victims and two suspects
• Police were called to the scene at 11:43 local time (19:43 BST) and "observed what appeared to be three deceased victims out front", San Diego Police Chief Scott Wahl said
• Two suspects, believed to be aged 17 and 19, were found dead in a nearby vehicle with self-inflicted wounds
• One of the deceased victims is a security guard who worked at the centre, Wahl said
• The police chief said the incident is currently being treated as a hate crime

• A witness speaking to CBS News, the BBC's US partner, says he heard up to 30 gunshots from what sounded like "a semi-automatic weapon"
• Nearby schools were placed on lockdown while police responded, with an aerial video showing children being escorted through the parking lot of the Islamic Center

Asked about the shooting at an unrelated event on Monday, US President Donald Trump calls it a "terrible situation".

"I've been given some early updates but we're going to be going back and looking at it very strongly," he says.

Shaimaa Khalil
Los Angeles Correspondent

Today’s shooting is a massive jolt to a community preparing for one of its holiest seasons and its biggest feasts.

We’re days away from Eid al-Adha or the "Festival of Sacrifice," one of the two major Muslim holidays, where families celebrate and commemorate the obedience of Prophet Ibrahim.

This is a very significant time in the Islamic calendar. We are currently in Dhul-al-Hijjah month, which is the 12th and final month of the Islamic lunar calendar

These days are considered the most sacred, spiritually significant 10 days of the entire year. The first 10 days of Dhul-al-Hijjah are highly revered.

This is the season of the Hajj Pilgrimage – with the day of Arafat, considered the holiest day of the year. at its heart.

Image source, Reuters

Imam Taha Hassane of the Islamic Center says "we have never experienced a tragedy like this before".

Speaking over the noise of sirens and helicopters, he says: "It is extremely outrageous to target a place of worship."

"I would like also to thank all the people that contacted us from across the country and overseas, to give condolences and to ask if there is anything they can do to help," he says, also thanking local police and FBI.

The press conference has finished, and police say they will be back in two hours time for another update.

Image source, Getty Images