2:02 a.m.: An off-duty officer working at the nightclub responds to shots at the entrance and exchanges fire with Omar Mateen. Mateen goes inside.
Mateen opens fire and patrons hide, duck and flee.
Police officers enter the building and engage in a gun battle with Mateen, which they say forced him to retreat to the restrooms. Witnesses report he moved in and out of the restrooms during the standoff.
2:30 a.m.: Mateen makes three 911 calls and during the conversations said that he was doing this was he wanted America to stop bombing his country, according to Patience Carter, a witness in the bathroom.
2:39 a.m.: Mateen returns to the restroom.
Around 5 a.m.: Witnesses hear explosions as police attempt to breach the building and say Mateen shoots more people. Police break through the walls and kill Mateen as he emerges.
Sources: Orlando Planning Commission, Times reporting. Graphics reporting by Charles Minshew / Orlando Sentinel