The explosion struck an area between Manchester Arena and the adjacent Victoria Train Station. Police say the first report came in at 10:33 p.m. local time — a time that seems to have been chosen because it meant crowds of concertgoers were starting to head home from the arena, which seats around 21,000.

After the large blast struck, chaos took over at the arena. In addition to at least one arrest, police tweeted Tuesday that they’ve “executed warrants, one in Whalley Range, and one in Fallowfield, where a controlled explosion took place.” gettyimages-687349446_custom-9e4c83c5855d70e63907bcf5f44db09646bc1244-s1600-c85Those areas are next to each other, roughly 5 miles south of Manchester Arena. No further information was released about the activity. Immediately after the attack, police received more than 240 calls about the blast. Investigators are asking people who were at the concert to share images and footage from the scene if they believe it might help the investigation. They’re also seeking any dashcam video recordings that drivers might have from 8 to 11 Monday night.”The attacker, I can confirm, died at the arena,” Chief Constable Hopkins said at a news conference. “We believe the attacker was carrying an improvised explosive device, which he detonated, causing this atrocity.” More than 400 officers were working on the investigation, according to Manchester police.