Police in California on Tuesday were investigating a deadly shooting at a mosque complex as a hate crime after two teenage gunmen killed three people a day earlier.
Monday's attack on the Islamic Center of San Diego has also drawn widespread national and international condemnation.
"We are actively investigating this as a hate crime," San Diego Police Chief Scott Wahl told reporters. "There was definitely hate rhetoric that was involved."
The Islamic center describes itself on its website as the largest mosque in San Diego County, which is in southern California.
"The suspects at this point appear to have died from self-inflicted gunshot wounds. There were no officers involved in firing their weapons," Wahl said.
NBC identified the shooters as Cain Clark, 17, and Caleb Vazquez, 18, citing three law enforcement officials.
Wahl said a security guard at the Islamic center was among the three victims, adding that his response had helped prevent a deadlier attack.
"His actions were heroic, and he undoubtedly saved lives today," Wahl said.
The identities of the victims were not immediately announced.
Wahl said that the mother of one of the suspects had contacted police two hours before the attack and reported that her son was "suicidal" and that several weapons and her vehicle were missing.
One of the shooters left a suicide note that contained writings about racial pride, and hate speech was scrawled on one of the weapons, CNN quoted unnamed law enforcement officials as saying.
The imam at the mosque, Taha Hassane, said that all the staff, teachers and children at the mosque's school were safe.
"We have never experienced tragedy like this before. And at this moment, all that I can say is, sending our prayers and standing in solidarity with all the families in our community here," he said.
"It is extremely outrageous to target a place of worship," the imam added.
President Donald Trump said the shooting was a "terrible situation," while New York Mayor Zohran Mamdani, the first Muslim mayor of a major American city, described the attack as "an apparent act of anti-Muslim violence."
"Islamophobia endangers Muslim communities across this country," he posted on X, adding that New York police are boosting deployments to mosques "out of an abundance of caution."
State Governor Gavin Newsom expressed horror at the attack, saying: "Worshippers anywhere should not have to fear for their lives."
"Hate has no place in California, and we will not tolerate acts of terror or intimidation against communities of faith," he said on X, adding, "To the San Diego Muslim community: California stands with you."
U.S. Muslim civil rights and advocacy group, the Council on American–Islamic Relations (CAIR), condemned the attack.
"The Islamic Center of San Diego is a pillar of the faith community in California and the broader American Muslim community. We strongly condemn this deadly attack and we welcome law enforcement's pledge to thoroughly investigate the motive for this crime. No one should ever have fear for their safety while praying at a house of worship or studying at an elementary school," CAIR said in a statement on X.
The Alliance of Australian Muslims (AAM) and the Australian National Imams Council (ANIC) also strongly condemned the attack and mass shooting.
"We extend our deepest condolences to the families of the victims, the Muslim community in San Diego, USA, and all those affected by this horrific act of violence. Mosques and places of worship must remain sanctuaries of peace, safety, and reflection, not targets of hatred and terror," it said in a statement.
"The Australian Muslim community remains deeply fearful and concerned about the risk of attacks targeting Muslims, mosques, Islamic schools, and community institutions. Recent threats, hate incidents, online extremism, and rising hostility have intensified these fears," the statement added.
