Two deaths near Occupy camps in Oakland and Burlington

Occupy Oakland protesters hold a candlelight vigil for the man who died near the protest camp

Police are investigating two fatal shootings at or near Occupy protest camps in US cities on Thursday.

A man was killed after a fight broke out close to the Occupy camp in Oakland, California, but it is not clear if he was a protester.

In Burlington, Vermont, a 35-year-old war veteran apparently shot himself in the head in a tent at an Occupy camp.

The shootings come amid strained relations between protesters and officials in some US cities.

Also on Friday, a 42-year-old man was found dead inside his tent at Occupy Salt Lake City in Utah.

Officials believe he died from a combination of drugs and carbon monoxide poisoning.

Police Chief Chris Burbank told protesters he was ordering police to arrest camp members if they did not leave two encampments in the city by sundown on Saturday.

According to the Salt Lake Tribune, Mr Burbank said he would understand if the demonstrators chose on principle to face arrest, but asked that they pack up their belongings beforehand.

Occupy Wall Street is in its second month of protest against corporate greed and economic inequality.

'Greatly concerned'

Police say the Oakland incident involved gunfire between two groups of men near the plaza outside City Hall on Thursday.

Occupy Oakland organisers have said the incident - the city's 101st murder this year - had nothing to with them, although police believe some protesters tried to defuse the situation.

One witness, John Lucas, 52, who is part of the Occupy Oakland medical team, said: "Several people went after one guy, and the group got larger, and they beat him and he ran.

"There were six or seven shots. Everyone starts running... and there was another shot."

When they found the man was not breathing, they tried to revive him.

The victim was pronounced dead at the hospital; no arrests have been made.

Oakland Mayor Jean Quan said on Thursday: "Tonight's incident underscores the reason why the encampment must end. The risks are too great."

She also said the protest was diverting police from tackling violence in the rest of the city.

Eviction deadline

The shooting happened just before the Occupy camp began celebrating its one-month anniversary.

On Wednesday, Oakland businessmen held a news conference asking for the camp to be disbanded as they said it was damaging trade and posing safety concerns.

Meanwhile, an unnamed military veteran died after shooting himself in the head in a tent in Burlington's City Hall Park, where that city's Occupy movement is based.

Police in Burlington, in the state of Vermont, said the shooting raised doubts about whether the protest should continue.

"When there is a discharge of a firearm in a public place like this it's good cause to be concerned, greatly concerned," said deputy police chief Andi Higbee.

Meanwhile, the mayor of Portland, Oregon, has given protesters until Sunday morning to vacate two city parks.

"Crime, especially reported assaults, has increased in the area around the camps," Mayor Sam Adams said, as he issued the deadline.