Florida School Shooting: 17 Killed, Several Injured at Marjory Stoneman Douglas High

Students were seen running for cover as the Florida High School was placed on lockdown.

The accused Florida school shooter made his first court appearance Thursday, speaking only two words in a very short hearing.

The 19-year-old replied, "Yes, ma'am," when a magistrate asked if he was Nikolas Jacob Cruz. He did not enter a plea and was denied bail. He hung his head and stared at the floor during his appearance.

The shooting claimed 17 lives and left several people injured Wednesday at Marjory Stoneman Douglas High, authorities said.

The campus was placed on lockdown as authorities led students to safety and first responders triaged the wounded.

Cruz, a former student, was taken into custody without incident about four miles away in Coral Springs on the eastern edge of the Everglades.

He was armed with at least one AR-15 assault weapon and multiple ammunition magazines, according to Broward County Sheriff Scott Israel.

"It's horrible. It's catastrophic," said Israel. Cruz had been expelled by the school, the sheriff said.

Authorities, who later tracked the teenager's internet posts, found several that were "disturbing," Israel said.

After receiving medical treatment for an undisclosed injury, Cruz was escorted to jail wearing a hospital gown. 

The alleged gunman pulled a fire alarm at the school to lure students into hallways, authorities said. 

“We were told last year that he wasn’t allowed on campus with a backpack on him,” said math teacher Jim Gard, who said Cruz had been in his class last year. “There were problems with him last year threatening students, and I guess he was asked to leave campus,” the instructor told the Miami Herald. 

Students cowered in classrooms and closets as round after round was fired on campus. Facebook Live footage showed students screaming and crying as loud gunfire is heard outside. 

12 people died inside the school, Israel said. Two died outside. Another was gunned down on a nearby street corner and two others died later while being treated in a nearby hospital. 

Frantic parents were held back by law enforcement officers as they begged for word on their children. Some students were seen clutching Valentines as they ran from the school. It was also Ash Wednesday and some parents carried the Catholic ash marking on their foreheads.

Students inside the school texted with family, warning them to stay away because they could hear the gunman's weapon being fired.

President Trump was among those tweeting his sympathies.

Wednesday's carnage marked the 18th school shooting of 2018.