Incorrect and missing records and an apparent lack of co-ordination among firefighters are complicating the clean-up after the massive explosions of hazardous chemicals warehouses that destroyed an industrial section of the Chinese port city of Tianjin.

The official death toll rose to 55 on Friday, with hundreds injured. Residents donated blood at hospitals as well as food and clothing to thousands of displaced people taking shelter overnight in schools. Many had fled in their nightclothes.

Hazardous chemicals teams removed sodium cyanide, a toxin, from sewers leading from the bonded warehouse zone that was at the centre of the Wednesday evening blast, Chinese media reported. On Thursday afternoon, authorities shut some of the drains leading into the nearby Bohai Bay.