A HUNT has been launched for a man who attacked two elderly people -- stabbing one of them in the face.

The man, believed to be white and in his late teens or early 20s, struck at two different addresses in the Waterloo area of Blackburn on Saturday.

In the first incident, he knocked on the door of a house at Bunker's Hill Close at about 9.10pm. The 86-year-old woman occupant put the security chain on before opening the door.

When she opened the door the man tried to force his way in. When he could not he thrust a knife through the gap, stabbing the woman in the face. Her elderly husband tried to get to the door but could not get there in time.

Just 20 minutes later at Heys Close, less than quarter of a mile away from the first incident, a 78-year-old man heard knocking at the door.

When he asked who it was, the offender said he was a police officer. The occupant opened the door, only for the attacker to burst through and set about him "some sort of weapon".

In both cases, the offender ran off immediately after the attacks. No property was stolen.

Det Sgt Paul Murphy, of Blackburn Police said they were linking the two offences.

"I have no doubt that this man has targeted elderly people," he said. "These are the only two addresses we believe he has knocked at.

"The fact he has attacked elderly people makes the offences even more callous.

"This man is obviously desperate and must be apprehended before he commits any more offences."

He also issued an appeal to older members of the community to be more security-conscious.

"I would them to make sure they have a security chain on their doors at night," said DS Murphy.

"Also, if anyone is called on by someone saying they are a police officer, ask them to show ID through the window and, if you are still unsure after that, don't hesitate to contact Blackburn Police Station and ask if they can confirm a police presence at your address."

Both victims were rushed to Blackburn Infirmary and were treated and later released.

Both are said to be in a state of shock.

If you have information, call Blackburn Police on 01254 51212.