Federal investigators on Saturday began searching for what caused a Boeing jetliner with 143 people on board to slide off a runway into a shallow river while landing at a Jacksonville, Florida, military base during a thunderstorm, injuring 22 people.

The Boeing 737-800 chartered by the U.S. military was arriving from Naval Station Guantanamo Bay in Cuba with 136 passengers and seven crew members when it slid into the St.

Johns River at the end of the 9,000-foot runway at Naval Air Station Jacksonville on Friday night, authorities said.

Officials raised the count of people injured to 22, from 21, after a three-month-old child was admitted to a local hospital for observation, Capt.

Michael Connor, commanding officer at the Jacksonville station, told a news conference.

He added that the status of the pets on board was still unconfirmed.

National Transportation Safety Board investigators have recovered an undamaged flight data recorder and it has been sent to Washington for analysis, NTSB Vice Chairman Bruce Landsberg said at the news conference.