TIANJIN, Nov. 29 -- Four people died after a minibus plunged into a river due to limited visibility caused by heavy fog in the northern port city of Tianjin on Saturday morning, local authorities said.

The accident happened at about 6:07 a.m. in Xiqing District, according to police.

Three people in the minibus, including the driver, escaped but four were trapped and died.

The cause of the accident is being investigated.