WELLINGTON, July 19 (Reuters) - New Zealand police said on Friday there had been a "serious" incident in the South Island city of Christchurch that left a house on fire after residents described hearing the sound of an explosion.
Police said in a statement initial reports suggested a number of people had been injured in the incident at about 10.20 local time (2220 GMT) in the residential suburb of Northwood.
A house was on fire and police had closed roads and were carrying out evacuations following a "serious incident".
The incident comes four months after a lone gunman killed 51 people and wounded dozens in attacks on two Christchurch mosques in New Zealand's worst peacetime mass shooting.
A Christchurch hotel worker, who was not identified, told the New Zealand Herald newspaper that a sound like an explosion had shaken nearby buildings.
"It was more than an earthquake, you'd think a bomb had gone off," the newspaper quoted the worker as saying.
Police did not identify the cause of the incident. (Reporting by Charlotte Greenfield Editing by Richard Pullin)