Eight people were traveling aboard the aircraft, which was on a humanitarian mission, the Mexican Navy Secretariat said in a statement.

Four people were rescued alive and two were killed, with efforts ongoing in coordination with the US Coast Guard to rescue two more people who were inside the crashed aircraft, the statement added.

The accident occurred as the aircraft was approaching Galveston, Texas.

The specialized medical transport mission was coordinated with a Mexican foundation that cares for children with severe burns.

According to the flight tracking website Flight Radar, the plane took off from Merida in Mexico's Yucatan state at 18:46 GMT and was last recorded at 21:01 GMT over Galveston Bay, near Scholes International Airport.