The coordinated massacre at Istanbul’s Ataturk Airport came into clearer focus Wednesday as officials revealed a more detailed timeline of the terror attack that killed 42 and wounded 238.

After the three attackers arrived at the Turkish transit hub via taxi on Tuesday, one of the assailants entered the terminal, began shooting people and then blew himself up near X-ray machines, officials said. During the chaos, a second attacker rushed to the departures level and detonated his explosives. The third attacker waited outside during the entire episode, blowing himself up as scared travelers frantically flooded out of the airport.

“When the terrorists couldn’t pass the regular security system, when they couldn’t pass the scanners, police and security controls, they returned and took out their weapons out of their suitcases and opened fire at random at the security check,” Turkish Prime Minister Binali Yildirim said Wednesday.

Several U.S. airports strengthened security measures due to the carnage in Istanbul, and, adding to the tension, a terminal at JFK Airport in New York was evacuated for a brief period Wednesday when a suspicious bag was spotted. It was later determined the unattended bag posed no threat and travelers were allowed back in the terminal.

Authorities viewed ISIS as the most likely culprit in the Istanbul attack, as the Turkey assault bore hallmarks similar to the March 22 coordinated terror attacks in Brussels, in which ISIS operatives killed 32 in coordinated bombings at Zaventem airport and a nearby metro station. But ISIS had not taken credit for Tuesday’s attacks, and Ankara has battled Kurdish militants as well as ISIS.

Report: 28 dead after attack in Turkey