A security guard who was killed during the shooting at a San Diego mosque on Monday is being hailed as a hero after police said that his actions “undoubtedly” saved lives.

On Monday, two teenagers opened fire at the Islamic Center of San Diego, California, shooting and killing three men. The two attackers, aged 17 and 18, were found dead several blocks away, from apparent self-inflicted gunshot wounds, officials said.

Among those killed was 51-year-old Amin Abdullah, a security guard at the center.

Speaking at a news conference on Tuesday, Scott Wahl, San Diego’s police chief, said that the two shooters ran past Abdullah, and that Abdullah “immediately observed the threat to everybody at the mosque” and “began to engage them with gunfire”.

“Both suspects returned fire,” Wahl said, adding that in the midst of the “gun battle” Abdullah reached for his radio, and “put out the lockdown protocol” for the center.

“His actions without a doubt delayed, distracted and ultimately deterred these two individuals from gaining access to the greater areas of the mosque where as many as 140 kids were within 15ft of these suspects,” Wahl said. “Tragically, he died in that gun battle.”

The two other victims were identified as 78-year-old Mansour Kaziha, described as a mosque elder and founding member of the center, and Nadir Awad, 57, who lived across the street from the center and whose wife worked as a teacher at the center’s school.

On Tuesday, Wahl said that Kaziha and Awad drew the attention of the attackers and drew them “back out into the parking lot area”.

Kaziha, Wahl said, was the first one who called 911.

In the parking lot, the two men “were unfortunately unable to flee”, police said, and the attackers cornered and killed them. Both suspects fled the scene and were found dead in a car nearby.

“I want to be very clear, all three of our victims did not die in vain,” Wahl said. “Without distracting the attention, without delaying the actions of these two individuals, without question, there would have been many more fatalities.”

At the news conference, the director of the Islamic Center of San Diego, Imam Taha Hassane, described the three victims as “brothers in the community” and called them “our martyrs and our heroes”.

He said Abdullah was “such a lovely person” who “never stopped smiling to anyone”.

“If it was not for him, as chief mentioned, the carnage would be much worse,” Hassane said. “He’s the one who stopped them, who slowed them down. If he didn’t do what he did and he sacrificed his life, the two suspects would have easily access to every single classroom.”

Hassane described Kaziha as the “pillar” of the Islamic Center. “I have never done anything without him.”

Awad, who he described as a neighbor, “rushed to do something” after he heard the gunfire.

“My community is mourning,” Hassane said. “My community is keeping our three heroes in their prayers.”

Mark Brimley, special agent in charge of the FBI’s San Diego field office, said on Tuesday that the victims were “there to help others be part of a community that came together in peace”.

“Instead, they were confronted by teenagers who appear to have been radicalized online to believe that they didn’t belong because of how they looked or where they worshipped,” he said.

At a separate news conference on Tuesday, Abdullah’s daughter, Hawaa Abdullah, remembered her father as “a loving father, husband, son, brother and uncle”.

“To me, my dad was a role model,” she said. “He was a best friend, the was the best absolute best dad in the world. He was my protector. My dad was a number one advocate for safety and keeping our communities safe. He stood against any form of hate.”

Police and FBI have said that they are investigating the attack as a hate crime.