Mourners gather Thursday at a vigil for the victims of the shooting at Marjory Stoneman Douglas High School.

Hundreds hoist their candles during a vigil Thursday evening in Parkland, Fla., for the victims of Wednesday's school shooting.

Isaac Briones, 15, carries balloons for one of his best friends, shooting victim Martin Duque, 14, as he tries to get close to Marjory Stoneman Douglas High School on Thursday. "He was, like, one of the nicest people I knew," said Briones. "He was so caring."

Waiting for word from students, anxious family members gather at Coral Springs Drive and the Sawgrass Expressway, just south of the campus, following a shooting at Marjory Stoneman Douglas High School in Parkland, Florida, on Wednesday.

Parents wait for news after reports of a shooting at Marjory Stoneman Douglas High School in Parkland, Fla., on Wednesday.

Police officers ride in the back of a pickup truck as they tend to a victim following the shooting at a Florida high school. Several of the wounded were undergoing surgery at local hospitals Wednesday afternoon.

Anxious family members wait for news of students as two people embrace Wednesday in Parkland, Fla.

An armored police vehicle arrives in response to the shooting at Marjory Stoneman Douglas High School in Parkland, Florida, on Wednesday.

People comfort each other as they wait for word from students.

In this image from video, students from the Marjory Stoneman Douglas High School in Parkland, Fla., evacuate the school following a shooting Wednesday.

Medical personnel tend to one of the people wounded in a shooting at a Florida high school on Wednesday.

Students are evacuated by police after Wednesday's lockdown was lifted.

Medical personnel tend to a victim following Wednesday's shooting. Police evacuated students and staff from the building.

Students embrace in the aftermath of a mass shooting at Marjory Stoneman Douglas High School in Florida.

Students released from a lockdown are overcome with emotion after a former student opened fire with an assault-style rifle at their high school.

Medical personnel tend to a victim following a shooting at Marjory Stoneman Douglas High School in Parkland, Florida, on Wednesday.

Students released from a lockdown embrace following Wednesday's shooting. Police identified the gunman as a former student.

People wait for word from students after Wednesday's shooting.

Students released from a lockdown are overcome with emotion following following a shooting at Marjory Stoneman Douglas High School in Parkland, Fla., Wednesday, Feb. 14, 2018. (

A woman consoles another as parents wait for news about a shooting at Marjory Stoneman Douglas High School in Parkland, Fla., Wednesday.

Family members pick up students of Marjory Stoneman Douglas High School at a nearby hotel, where they were taken after a former student opened fire at the Florida school Wednesday, killing at least 17 people and sending scores of students fleeing into the streets.

Reunited families leave the the Marriott Coral Springs Hotel on Wednesday night, hours after the deadly shooting at Marjory Stoneman Douglas High School.