YOBS are believed to have set off a fire extinguisher through the letter box of a student house in Colchester's Greenstead estate, sparking a chemical alert.

A group of girls were at home in Sycamore Road when the vandals struck.

When the white mist cleared they phoned the police's non-emergency number for advice.

Minutes later police, fire, ambulance and a hazardous material team turned up and evacuated the property and sealed off the area.

It is believed the powder was from a fire extinguisher.

Ria Devereux, 19, who is studying marine biology at Essex University, said: “We had been cleaning it up and then when they all came they said we may be contaminated.”

It is a relief to find out what it was but we still had to clean it up.

“It was shocking. We think it was kids with what else has been happening.”

The students and their neighbours have had eggs thrown at their homes, paint has been thrown over cars and garages and residents have reported gangs of youths banging and kicking on doors in the early hours of the morning.

Fellow housemate Kelsey Miller, 20, praised the exceptional emergency services for their quick response but is angry about the disruption.

She said: “The white powder was all over the hall and went everywhere. Under a locked cupboard, behind the sofa in the lounge, everywhere.

“We thought it was a flour bomb but there was a chlorine smell.

“None of us freaked out and we are glad it was nothing else but now have to clear it up and hope it does not happen again.”

The incident happened on Thursday at  7.30am.

Anyone with information call Colchester police station on 101.