Aviation officials in Pakistan say a search operation is ongoing after a cargo plane carrying five crew members went missing off the coast of Karachi, a city at the country’s southern tip.

The Boeing 737 rapidly descended and lost contact with air traffic controllers on Tuesday at 21:21 local time (16:21 GMT), Pakistan’s airport authority said. The plane had been en route to Karachi from Sharjah in the United Arab Emirates.

It had reported a navigation system problem minutes before its descent, the airport authority said.

The plane was operated by K2 Airways, a private cargo airline based in Karachi. The company was founded in 2018, according to its website.

In a statement on Wednesday, K2 Airways identified the five crew members on board the aircraft, and said it was “fully cooperating with the Pakistan Civil Aviation Authority and other government agencies”.

“We continue to pray, earnestly, for the safety of our colleagues,” the statement said.

According to preliminary data from Flightradar24, a flight-tracking platform, the plane recorded a sharp fluctuation in altitude before a steep descent.

Various agencies, including the navy and air force, have been deployed to look for the missing plane, the airport authority said.

The last major aviation incident in Pakistan involved a domestic passenger flight in 2020. In that incident, a Pakistan International Airlines plane crashed while approaching Karachi airport, killing all but two of the 99 people on board.