Police are hunting for the gunmen who shot dead two teenage girls and injured two others outside a New Year party.

Charlene Ellis, aged 18 and Latisha Shakespeare, 17, were shot outside a hairdressing salon in Birmingham on Thursday.

Charlene's twin sister Sophie and 17-year-old Cheryl Shaw were both described as "stable" in hospital.

A crime expert has warned people in the area may be too frightened to help the police or give evidence.

'Exceptional brutality'

The four girls, who are all from Birmingham, had stepped out of the party at the Uniseven Studios hairdressing salon in Birchfield Road, Aston, at 0400GMT to cool off, when they were hit by a stream of bullets.

Launching a murder inquiry, police describing the shootings as "exceptional in their brutality" and "unprecedented".

Forensic officers worked through the night into Friday morning, examining the scene and a bullet-ridden car found nearby.

There has clearly been some sort of dispute Chief Supt David Shaw

A ballistics expert concentrated on spent rounds found on the ground at the rear of the hairdressers.

One possibility detectives are examining is that there was an exchange of gunfire between two gangs.

Chief Supt David Shaw, the police area commander for Aston, said extra armed officers were being deployed on the streets of the city in response to the killings.

'Almost unprecendented'

"There has clearly been some sort of dispute which has resulted in people coming to the premises with guns, discharging their weapons and causing this incident," he said.

"In my experience, and those of all the officers here, we have never had to deal with anything like this.

Police found three injured girls at the scene

"In terms of the nature of the incident, it's almost unprecedented in Birmingham.

"They (the shootings) are exceptional in their brutality."

He appealed for help from the local community to find the gunmen.

The 20 shops around the hairdressers remain closed.

Criminologist and former West Midlands police officer Doug Sharp said: "The fear in the community, the fear of reprisal means the police are going to have a very difficult job unless the public are willing to come forward."

He said in 2002, West Midlands Police arrested 57 people for gun-related offences and seized 92 illegal firearms.