At least 58 people going to a funeral died after their overloaded river boat capsized in the Central African Republic's capital Bangui, the head of civil protection said on Saturday.

"We were able to extract 58 lifeless bodies," Thomas Djimasse told Radio Guira. "We don't know the total number of underwater people.

According to witnesses and videos on social media, the boat was carrying more than 300 people -- some standing and others perched on wooden structures -- when it sank on the Mpoko River on Friday.

The vessel was heading to the funeral of a village chief but got into difficulty shortly after setting off. Rescue services arrived 40 minutes after the disaster.

Maurice Kapenya, who was following the boat in a canoe because there was no space on board, said he collected the bodies of some of the victims, including his sister, with the help of fishermen and residents.

Some of the injured were evacuated by motorbike taxis. Driver Francis Maka told AFP he had "taken more than 10 people to the community hospital... free of charge, in the face of the tragedy".

With civil protection teams no longer on the scene Saturday, families searched for their missing loved ones near the river and helped canoe operators they had hired, an AFP journalist observed.