Explosions mystify police and residents in south

Mysterious explosions that rocked Blenheim and Greymouth on Friday night have baffled police and residents.

Constable Paul Webber from Blenheim police said about 30 people reported hearing a series of bangs about 9pm. He suspected youngsters had lit plastic bags filled with gas.

"It was loud enough to rattle windows across town so would be dangerous for someone standing near it."

People on the Trade Me message board reported "serious boom noises".

One said it "sounded like an asteroid hit the planet".

Another mysterious explosion was heard in Greymouth about 8pm.

Greymouth police received a couple of calls, but had no explanation yesterday.

"We have spoken to the mines in the area and it was nothing to do with them," a spokesman said.