A cargo plane, identified as a Boeing 737-400, has gone missing over the Arabian Sea on Tuesday night with five crew members on board.

The aircraft was being operated by K2 Airways, a Pakistani airline, and had departed from Sharjah in the United Arab Emirates, heading towards Karachi. According to Pakistani aviation authorities, the crew reported a problem with the navigation system before all contact with air traffic controllers was lost. Preliminary data from Flightradar24 shows that the plane experienced a sudden loss of altitude, followed by a climb and then another sudden descent, possibly resulting in it crashing into the sea. The data suggests that the plane disappeared off the coast of Pakistan.

Rescue operations have been launched, with the Pakistan Navy and Air Force leading the search effort. Prime Minister Shehbaz Sharif has ordered for the operations to be intensified, but no updates have been given on the condition of the crew. Sharif extended his condolences to the families of the crew members.

K2 Airways stated that the crew consisted of two pilots, two engineers, and one support staffer, and they are working with the Pakistan Civil Aviation Authority in response to the incident. According to sources, the missing 737 was the only aircraft in K2’s fleet.

Boeing has yet to make a statement regarding the incident.

This is an ongoing story and will be updated as more information becomes available.