SAN SALVADOR - El Salvador's National Civil Police (PNC) on Monday were investigating the crash of a small plane that killed the pilot and two Chinese nationals in a region close to the capital.

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The reason for the crash remained a mystery as the YS 300 ED aircraft had undertaken a test flight, said the PNC. It crashed minutes after taking off from the Ilopango airfield some 10 km east of San Salvador Sunday afternoon.

"There was nothing out of order," said Alirio Serrano from El Salvador's Civil Aviation authority.

The two Chinese, Li Guoliang, 58, and Yu Wenkai, 42, were in Salvador on business on behalf of a Chinese aircraft company from Wuxi, China's eastern Jiangsu province.

They died alongside the pilot Yaron Degani, a Salvadoran of Israeli origin.

Degani, 56, had lived in El Salvador for over 20 years where he had funded the Pulsar Group, a company which has specialized in the manufacturing of a variety of spare parts for small airplanes since 2005 and has recently participated in a bidding to supply aircraft to the Salvadoran Armed Forces.

Serrano told local press that the plane had gone to an altitude of about 500 feet and crashed about 500 meters from the landing strip. "Local air traffic controllers said they heard a noise and then a shout."

Degani had invested $2 million in setting up his factory at the Ilopango airport, and the Pulsar Group had been involved in the construction of over 700 light planes.