HANOI, July 16 (Xinhua) -- Rescuers were searching for three Vietnamese fishermen who went missing after a fishing ship collided with a cargo ship in Vietnam's northern Quang Ninh province, provincial authorities said on Monday.

The fishing ship, registered in northern Hai Phong city, collided with an identified cargo ship near Co To island in Quang Ninh early Sunday, which threw seven fishermen into the sea.

Four fishermen were rescued and brought onshore for medical treatment.

The ongoing search on Monday was hampered by strong winds and high waves, authorities said.