Washington, Aug 14 (IANS): A clash erupted between police and demonstrators in Wisconsin state of the US after a police official shot dead an armed man, the media reported on Sunday.

A gas station and a vehicle were set on fire in Milwaukee city of the state when about 100 protesters gathered at a predominately African-American part of the city where two police officers on Saturday pulled over a car with two suspects inside, Xinhua news agency reported.

According to witnesses, gun fires were heard as police officers wearing riot gear tried to disperse the protesters. At least three persons were detained.

A police officer was hit in the head by a brick, the witnesses said.

On Saturday, the police officer shot dead one of the two 23-year-old suspects as they tried to escape. The name of the suspect or the officer remain undisclosed.

The police officer, who shot and who was not hurt, was placed on administrative leave while an investigation into his conduct was launched.

The second suspect was in custody, a police official said.

The man who was killed carried a stolen handgun and has "a lengthy arrest record", which he failed to specify, he said.

Milwaukee Mayor Tom Barrett, appealing for restraint and calm, acknowledged that the neighbourhood, where the shooting took place, had been affected by violence in the recent past.

"There are a lot of really, really good people who live in this area...and can't stand this violence," Barrett said.

The incident was preceded by several police-involved shootings across the US, in which the use of force by police has been questioned.

In July, two black men were shot dead by police in Louisiana and Minnesota, which sparked angry protests by African Americans across the nation against police brutality and racial discrimination.