Five Seattle 
police officers were injured and at least nine people arrested on Sunday
 night, after unruly demonstrators hurled projectiles and Molotov cocktails and broke windows, authorities said.
Protesters
 gather every year on May 1 to focus attention on labor and immigration 
issues, but demonstrators in cities across the United States also used the occasion to rally against police violence.
Mayor
 Ed Murray blamed the "senseless violence" in Seattle on a "different 
crowd" from those who had attended an earlier peaceful May Day 
immigration march, however.
It was "deeply 
regrettable that in a city that goes to incredible lengths to respect 
First Amendment rights, there are some who disregard our values and 
engage in senseless acts of violence and property destruction," he said later, referring to free speech protected by the U.S. Constitution.
In
 posts on social media website Twitter, the Seattle police department 
said one officer had suffered a cut to the head as protesters hurled 
Molotov cocktails, another was hit by a rock, and a third officer was 
bitten, apparently by a protester.
Injuries suffered by two more officers were not detailed.
"Nobody has been seriously injured," police chief Kathleen O'Toole said after the unrest subsided, adding, "Once assaults started and property damage started, we took action. It's that simple."
Police
 said they made arrests in several places and restrained one group in a 
parking lot, before allowing some groups to disperse, but would maintain
 a presence in the area.
They charged three people
 with assault, one with destruction of property and five with 
obstruction of justice. Eight men ranging in age from about 20 to 32 
were charged, along with a teen-aged girl.
Police 
used "blast balls" to disperse a crowd throwing rocks and bottles and 
breaking windows in a downtown neighborhood, the Seattle Times newspaper
 reported, after they used pepper spray several times to break up 
throngs of demonstrators.
The unrest mirrored 
violence at a Seattle May Day march last year, when crowds threw bottles
 and wrenches at police, who responded with pepper spray and flash 
grenades.
Sixteen people were arrested and three 
officers hurt in that violence, which similarly erupted after a day of 
peaceful demonstrations.
 
 
   