Authorities are investigating one of India’s worst aviation disasters a day after an Air India plane crashed, killing all but one of the 242 passengers and crew onboard, officials said Friday, as Prime Minister Narendra Modi visited the crash site.

Prime Minister Narendra Modi said he was “devastated” after visiting the site of Thursday’s plane crash in western India, where more than 240 people were killed.

Air India Flight 379, which left the Thai island of Phuket this morning en route to New Delhi, landed back on the island shortly after takeoff, according to flight tracker Flightradar24. All 156 passengers were escorted from the plane as is standard in emergencies, Reuters reported, citing an Airports of Thailand official.