A student pilot and his instructor were killed today when the their small plane collided mid-flight with a passenger plane a short distance from a Nairobi airport, police said.

Kenya’s Civil Aviation Authority said it was investigating the cause of the “accident” involving a Ninety-Nines Flying School Cessna training aircraft and a Safarilink Airlines Dash 8. He did not specify how many people were killed.

Nairobi police chief Adamson Bugei said two people were killed, the trainee pilot and his instructor.

Ninety-Nines Flying Club, listed on its website as a “private and commercial sector” pilot school, confirmed the crash without further details when contacted by AFP.

For its part, Safarilink said the 39 passengers and 5 crew members of the flight bound for the Diani resort heard “a loud explosion shortly after take-off” from Wilson Airport in the morning. The plane immediately returned to the airport, although none of the passengers and crew were injured. Safarilink serves 18 destinations in Kenya and neighboring Tanzania.

The small Wilson Airport is located to the south of Nairobi and is the main departure point for domestic flights to the country’s beaches and national parks. It is 15 km from Jomo Kenyatta International Airport, the largest in the country.