Protesters attacked Donald Trump supporters on the sidelines of a San Jose rally Thursday night, in a raucous scene where a dozen or more people were punched and at least one woman was pelted with an egg.

Protesters also reportedly grabbed Trump hats from supporters and set the hats on fire on the ground.

Police eventually moved into the crowd to break it up and make arrests. At least four people were taken into custody, though police didn't release total arrest figures Thursday night. One officer was assaulted, police Sgt. Enrique Garcia said.

Mixed accounts emerged overnight over to what extent the Trump supporters were taunting the protesters. KTVU reported that the woman who got hit with an egg was “making gestures back at” the protesters. But the same report said the crowd of demonstrators had surrounded and trapped her at the time, and video of the incident appeared to support that account.

Hillary Clinton campaign chairman John Podesta took to Twitter to condemn violence against "supporters of any candidate."

There were no immediate reports of injuries and no major property damage, police said.

The crowd, which had numbered over 300 just after the rally, had thinned significantly but those that remained, filling about a city block near the San Jose Convention Center, were rowdy and angry.

Some banged on the cars of Trump supporters as they left the rally and chased after those on foot to frighten them.

Police were keeping their distance from the crowd as the scuffles played out, but keeping them from getting any closer to the convention center.

"Our police officers have done an extremely courageous and professional job so far," San Jose Mayor Sam Liccardo told The Associated Press by phone. "We're all still holding our breath to see the outcome of this dangerous and explosive situation."

The mayor, a Democrat and Hillary Clinton supporter, criticized Trump for coming to cities and igniting problems that local police departments had to deal with.

"At some point Donald Trump needs to take responsibility for the irresponsible behavior of his campaign," Liccardo said.

The presumptive GOP nominee spoke for about 50 minutes at the rally, sniping at Democratic candidate Hillary Clinton and calling her speech on foreign policy earlier in the day "pathetic" and "sad to watch."

Protesters before the speech included Adam Rivas, a 22-year-old community college student who was born and raised in San Jose, was holding a spray-painted sign that read "Dump Trump."
Rivas said he was particularly disturbed by Trump's remarks about Mexicans.

"For any one Mexican here he bashes, there are about 20 Mexicans out there who are hard-working and just doing their job," he said.

Trump supporter Debbie Tracey, a U.S. Navy veteran from San Jose, she came to hear Trump speak, she left his rally with two hats a T-shirt and a handful of signs that said "Veterans for Trump."

Passing in front of a wall of protesters, many chanting in Spanish, she said she supported Trump's call for a wall along the U.S.-Mexico border.

"I'll go help build the wall because if you are going to come to this country, land of opportunity, you should be here legally," she said.

The Associated Press contributed to this report.