PARKLAND, Fla. – In a matter of minutes, students at Marjory Stoneman Douglas High School went from having a normal Wednesday to experiencing the most terrifying day they would ever experience at school when they began fighting for their lives.
Bullets sprayed the inside of one of the school buildings when a former student opened fire with an AR-15 rifle, killing 17 people, both adults and children, and injuring several others, according to the Broward County Sheriff's Office.
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On Thursday, deputies released the following timeline of how Wednesday's tragedy unfolded, according to video and other evidence collected throughout the investigation:
Wednesday, Feb. 14.
2:19 p.m.
An Uber driver dropped 19-year-old Nikolas Cruz off at the high school.
Cruz, the suspect, then entered the east stairwell of building 12 with the rifle, which authorities said was purchased legally within the state last year, inside a black soft case.
When Cruz exited the stairwell, he removed the rifle from the case.
2:21 p.m
Cruz readied the rifle for firing and began shooting into rooms 1215, 1216 and 1214. He then returned to fire more shots into 1216 and 1215 before shooting into room 1213, according to investigators.
After firing several shots into the rooms, the suspect took the west stairwell to the second floor and shot one victim in room 1234.
Cruz then took the east stairwell to the third floor, dropped the rifle and his backpack and ran down the stairs before leaving building 12 completely and running toward tennis courts.
Deputies said he then began fleeing southbound on foot until he crossed fields and began running with a group of students who were running in fear of their lives.
The sheriff said Cruz tried to blend in with the group of scared students until he eventually ran to a nearby Walmart and bought a drink at the Subway restaurant inside the store.
The suspect fled from the store on foot after purchasing the drink and ran to a nearby McDonalds, where he stayed for a while.
2:53 p.m.
The Broward County Sheriff's Office begins investigating reports of an active shooter at the school. When deputies arrive, they see hundreds of students fleeing.
3:01 p.m.
Cruz left the McDonalds on foot.
The alleged gunman mixes in with the students and staff running out of the school.
3:11 p.m.
The FBI and dozens of police vehicles respond to the shooting.
Video shows some students lying on the ground, being treated for injuries and moved into ambulances.
White House Press Secretary Sarah Sanders says President Donald Trump was briefed on the incident and is monitoring the situation.
3:15 p.m.
The gunman is still at large.
3:40 p.m.
The school begins dismissing students. Buses take them to a nearby hotel where they reunite with their families.
3:41 p.m.
The suspect was taken into custody by Coconut Creek police officers at 4700 Wyndham Lakes Drive in Coral Springs, deputies said. Investigators did not say whether they knew where Cruz was from the time he left McDonald's until he was detained.
3:50 p.m.
President Trump tweets, "My prayers and condolences to the families of the victims of the terrible Florida shooting. No child, teacher or anyone else should ever feel unsafe in an American school."
3:53 p.m.
Law enforcement searches the school's buildings to evacuate students from classrooms.
[READ: How Florida agencies are helping in response to school shooting]
4:10 p.m.
Authorities find Cruz in a nearby neighborhood and arrest him without incident. They identify him using school security videos.
He is taken to the Broward Health North hospital because he has "labored breathing." Cruz is treated and released to police custody.
4:20 p.m.
Broward County Public Schools Superintendent Robert Runcie says the school received no warnings and that he was not aware of any threats against the school.
5:18 p.m.
Florida Gov. Rick Scott travels to Broward County to be briefed about the shooting.
6 p.m.
Authorities identify the alleged gunman as Nikolas Cruz, a 19-year-old former student at the high school. He arrives at the Broward County Sheriff's Office wearing a hospital gown and is escorted inside by deputies.
6:30 p.m. to end of day
School district officials say the school will remain closed for the rest of the week.
The FBI sets up a website for students and others who were inside the school to upload videos and photos of the shooting.
Law enforcement officials search Cruz's home and another undisclosed location.
Thursday, February 15
6:11 a.m.
Cruz is charged with 17 counts of premeditated murder.
10:15 a.m.
Authorities hold another press conference, during which FBI officials reveal that an alarming comment was made on social media last year. The special agent could not confirm whether it was made by Cruz.
Florida Gov. Rick Scott and Attorney General Pam Bondi discuss meeting with victims' families and efforts to respond to the tragedy.
Sheriff Scott Israel unveils plans to release a timeline for the shooting later Thursday.
11 a.m.
President Trump announces plans to visit South Florida while addressing the nation in regards to the shooting.
[READ: President Trump to visit South Florida after mass school shooting]
12:05 p.m.
Florida U.S. Sen. Bill Nelson discusses the shooting from the Senate floor, followed by remarks from Sen. Marco Rubio.
5 p.m.
Sheriff Israel unveils timeline of Wednesday's tragedy during a press conference, followed by a reading of the names of the 17 victims killed in the school shooting.
FBI officials elaborate on comment made on social media last year, saying it was from a YouTube account linked to the name Nikolas Cruz, but was later removed from the website by YouTube.
The sheriff says the rifle was purchased legally at a dealership in Coral Springs called Sunrise Tactical.
The school superintendent announced that the school would remain closed through Friday and that officials are working to figure out what plans need to be in place before students would be able to return to the building where the tragedy took place.
Sheriff Israel says the medical examiner is working to release the victims to their families in a timely manner.
Grief counselors will continue to be available to students and others affected by the tragedy as they are needed, the superintendent said.
Detectives conducted more than 2,000 interviews Thursday afternoon and are still investigating the shooting.
CNN contributed to this report.