NAIROBI, Kenya – As Al-Qaida-linked terrorists threw grenades and fired automatic weapons, the three plainclothes Kenyan police officers, lightly armed and wearing no bulletproof vests, helmets or other protective gear, worked their way to the roof of Nairobi's Westgate Mall and led frightened shoppers to safety.

"I will be forever grateful for those three brave and selfless Kenyans," said Lyndsay Handler, an American who was among those rescued from the roof in the first hours of the siege that began Saturday.

"Words cannot fully capture the depth of this gratitude, but anyone who has come close to losing a child or spouse can understand."

Undercover police armed only with pistols and walkie-talkies like those who rescued Handler and her husband and 2-year-old daughter helped save countless lives in the initial minutes of the attack — heroics the New York native and others they brought to safety say have gotten too little attention.

Handler was in the shopping complex with her husband, Nick, and their 2-year-old, Julia. Father and daughter were at the popular eatery, Artcaffe, when about a dozen Al-Shabab militants descended on the upscale mall popular with foreigners and wealthy Kenyans and began firing indiscriminately.

Lyndsay, upstairs at a bookstore, headed to the roof, while Nick took shelter with Julia in a ground-floor storeroom of the mall's flagship department store, Nakumatt.

Father and daughter huddled for three hours until plainclothes police came to their rescue.

"It's hard to describe the relief I felt when I saw the doors to the storeroom open, and several incredibly brave plainclothes police, weapons drawn, motioned for us to leave as quickly as possible," said Nick Handler, of the Philadelphia suburb of Merion, Pa.

"Perhaps it was not rational, but I instantly trusted these guys with our lives. I felt a surge of hope that we were going to be fine."

Handler, 31, who works on agricultural issues in western Kenya, said the officers rushed into the attack zone "knowing that they were up against heavily armed gunmen and were putting their own lives on the line."

Video from inside the mall shows how security personnel worked to save lives. In one, a man thought to be a plainclothes police officer was seen scooting on his belly across the shopping center's ground floor to coax a mother and her two children lying next to a cafe counter to stand up and rush out.

The gunmen appeared to specifically target the unarmed guards as they began their attack, said Ben Mulwa, a community organizer who was shot in the leg near one of the mall entrances. One of the guards was shot through the head just feet from where Mulwa was hiding.

Individual acts of courage aside, however, Mulwa and other Kenyans questioned how prepared the country is to confront a large-scale attack. Kenya has been hit by terrorists in the past, and Western officials have warned that malls and other public spaces could be targeted.

"The fact that kind of gunfire can go on in a prime location like that ... I think the response probably wasn't as good as it could be," Mulwa said. "There's some lapses that need to be addressed."

It wasn't until late Tuesday that President Uhuru Kenyatta declared the terrorists had been defeated. Mopping-up operations continued into Wednesday, and occasional gunfire could still be heard from the mall.

The official civilian death toll stood at 61 late Tuesday, but officials said more bodies could still be inside the mall, and 71 people remain missing, according to the Red Cross. Six Kenyan security forces, as well as five Al-Shabab militants, also were killed.

Among the six Kenyan troops killed, three were first-responder police officers accidentally gunned down by Kenyan army officers in the chaos after the attack, police officials said.