Florida school shooting: Math teacher describes how he and students took cover

PARKLAND, Fla. -- Jim Gard, a math teacher at Marjory Stoneman Douglas High School, locked himself and several students inside his classroom during a gunman's deadly rampage. Moments before the chaos, school's fire alarm went off around 2:20 p.m. on Wednesday, he recounted.  

"Then we got an announcement that said, 'OK, evacuate the building,' like 10 seconds later. So I opened the door, the kids took off," Gard told "CBS Evening News" anchor Jeff Glor.

"So as I'm ready to leave, then we hear all these popping sounds," he described. "It sounded like firecrackers."

The announcements came back on and they heard, "Code red, get back in the room." Gard shuttled six students into his classroom and told them, "I don't know, this might be a drill."

"And then really 20 minutes later we knew it wasn't," Gard said.

Teachers were emailing which students were with them and who were missing, Gard described, and students were texting to locate other classmates. Around 4 p.m. they were released.

Police said a former student, 19-year-old Nikolas Cruz, killed 17 people and wounded more than a dozen others at the high school. Student Jamie Guttenberg and assistant football coach and security guard Aaron Feis were among the victims. Feis was shielding students from the gunman when he was shot.

Gard said he knew of two teachers who were shot and killed.

"One was shot and killed standing in front of the kids, which I'm not sure if you guys have his name released or not. But it doesn't surprise me. At all. I've known him since I got here in 2008. He was [a] fantastic person. He went here. He was an Eagle. He went here. He was a great guy," Gard said. 

Cruz fled the school and was captured by police a short time later. He was charged with 17 counts of premeditated murder Thursday after being taken to the Broward County jail. Officials say Cruz brought an AR-15 semi-automatic rifle and multiple magazines of ammunition to the school. He also wore a gas mask and carried smoke grenades.