Hundreds of LAPD officers, dressed in protective gear, evicted Occupy L.A. protesters from an encampment around Los Angeles' City Hall Wednesday morning in one of the largest police operations in recent memory.

Updated Article: Cleanup Begins Outside LA City Hall

By 4:30 a.m., about 200 people had been arrested in a mostly peaceful operation, according to the LAPD. Three people and a dog remained in a tree house at the encampment early Wednesday.

"At approximately 12:30 a.m., the LAPD began enforcing the closure of City Hall Park after giving those in the park a final opportunity to leave without facing arrest," Mayor Antonio Villaraigosa said in a statement.

Shortly before police issued their final edict for protesters to leave, some 500 helmeted LAPD officers -- some in Hazmat uniforms -- burst out of City Hall doors and raced into the Occupy L.A. encampment and began to arrest a few of the protesters.

Another 1,200 officers remained stationed around the area, breaking up the large crowd into smaller, more manageable groups, and preventing other outsiders from joining the protest.

Nearly 500 protesters had been congregating at the park, many chanting "We are peaceful" and "We are the 99 percent."

Police took a slow, methodical approach making arrests, careful to avoid any violent confrontations with protesters.

Villaraigosa called the city's response a "measured approach" and said the city wanted "give people every opportunity to leave peacefully."

LAPD Officer Karen Rayner of the Media Relations Section said officers were escorting protesters out of the area who decided to leave.

Four injuries were reported during the operation. Two were transported to a hospital but the extent of their injuries was not known.

Four off-ramps from the northbound and southbound Hollywood (101) Freeway had been closed since 10:04 p.m. Tuesday due to the impending action to clear the park, said Officer Anthony Martin of the California Highway Patrol.

Fliers were distributed to Occupy Los Angeles campers throughout Tuesday requesting they vacate City Hall Park prior to 10:30 p.m.

Mayor Antonio Villaraigosa first announced that by 12:01 a.m. on Nov. 21, occupiers would have to leave the encampment they have called home for two months. However, the deadline came and went without a police raid.

The eviction deadline did lead half of the encampment to fold up their tents and exit the lawn.

He later told the Los Angeles Times he decided to officially pull the trigger after learning there were children living in the tent city.

“The chaos out there could produce something awful,” he told the Times.

Occupy LA founding members and interfaith, community and labor supporters released a statement Tuesday night requesting a nonviolent resolution to the standoff between police and demonstrators.

“The Los Angeles Police Department has demonstrated a willingness to respect the civil right of protesters,” founders stated in the statement. “We call on them to continue to demonstrate that restraint and respect.”

Follow NBCLA for the latest LA news, events and entertainment: Twitter: @NBCLA // Facebook: NBCLA