A search is underway for the missing cargo plane off the coast of Pakistan.

Pakistan’s aviation authorities say a search operation is underway after a cargo plane carrying five crew members went missing off the coast of Karachi, in the southern tip of the country.

The Boeing 737 made a rapid descent and lost contact with air traffic controllers at 21:21 (16:21 GMT) on Tuesday, Pakistan’s airport authority said. The plane was en route to Karachi in Sharjah, United Arab Emirates.

Minutes before landing, he had reported a problem with the navigation system, airport officials 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 said it was “in full cooperation with the Pakistan Civil Aviation Authority and other government agencies” to identify the five crew members on board.

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

Preliminary data from Flightradar24, a flight-tracking platform, showed that the plane had experienced significant altitude fluctuations before descending.

Various agencies, including the Navy and the Air Force, have been deployed to search for the missing plane, the airport authority said.

The last major aviation event in Pakistan was in 2011. It will include domestic passenger flights by 2020. In this case, a Pakistan International Airlines plane crashed on approach to Karachi airport, killing all but two of the 99 people on board.