CHICAGO (CBS) — A total of Democratic National Convention in Chicago, police said, including about ten people from a small group of agitators who breached the outer security fence in front of the DNC during a much larger protest march.

Chicago Police Superintendent Larry Snelling estimated that 3,500 protesters marched Monday afternoon from Union Park, a few blocks from the United Center, to Park 578, just north of the arena, before returning to Union Park. The vast majority of them remained peaceful.

The protest was a sign of solidarity with Palestinewith activists calling for a ceasefire in the Gaza Strip and an end to US funding of Israel.

Snelling said a small group of troublemakers within the larger protest crowd removed locks from parts of the United Center’s outer perimeter fence and tore down parts of the outer security fence around 4:30 p.m. Some people got through a gap in the fence and tried to tear down a second level of the fence, but police were able to stop them.

“It was a brief break,” Snelling said.

Snelling said some of the people who had passed the perimeter fence threw water bottles and other objects at police, and some in the crowd sprayed officers with pepper spray. Officers suffered only minor injuries.

“We will not tolerate vandalism and violence in our city and we are ready, willing and able to respond to such things. That is why we will continue to protect the city,” Snelling said. “I could not be prouder of how the Chicago Police Department responded under these circumstances. We demonstrated the training and preparation that we have been doing for over a year.”

A total of 13 people were arrested on Monday in connection with the DNC. Snelling said about 10 of those people were arrested in connection with breaching the security fence and are facing charges including trespassing, resisting and obstructing police and aggravated assault against police officers.

“Our officers did not overreact. We were able to clear the area very quickly,” Snelling said.

Snelling said the security perimeter around the United Center has since been beefed up to prevent further break-ins during the DNC. On Tuesday morning, officers were seen adding an additional layer of fencing to the perimeter.

US Secret Service Democratic National Convention Coordinator Jeff Burnside declined to comment on further changes to the security perimeter, but confirmed that further repairs were being made to the security fence.

“We take a layered approach to all of our safety measures and we’re constantly working with our state, local and federal partners to evaluate, make improvements, make adjustments, and that’s all we’re doing,” Burnside said. “Our plan was in place, our plan worked. We’re taking some of our lessons learned and making the necessary adjustments.”

The Chicago chapter of the National Lawyers Guild said two of those arrested Monday were hospitalized and claimed they were assaulted by police. However, Snelling denied this and insisted the two were taken to the hospital to receive necessary medication.

“The officers responded perfectly and we have body camera footage to prove it. They were not hospitalized for injuries. As a police department, when we arrest someone and they are taking or need medication, we make sure they get it,” Snelling said.

Brad Thomson, a volunteer attorney with the National Lawyers Guild, said they were aware that two protesters had been hospitalized for medical treatment, but two others had been hospitalized for injuries sustained during their arrest.

Despite the fence breach, Snelling said the CPD did not need to change its public safety strategy during the DNC.

“We cannot predict every situation that might arise, but if we respond and stop it before it gets bad, then we have done our job,” he said.

Snelling said the vast majority of those attending Monday’s march were peacefully exercising their First Amendment right to free speech, but a small group decided to stay behind after protesters began to leave the area and breached the fence.

“The people who decided to commit crimes and vandalism stayed behind. We responded to this incident with our officers who were properly trained to handle the situation and as a result, no serious violation occurred, which could have been worse had we not been prepared,” he said.

Snelling is convinced that the police officers who responded to the breach of the fence showed due restraint in their arrests.

“Officers could have used more force in some situations yesterday than they did, and they showed great restraint. We will always face resistance to our response. There are people out there who believe we shouldn’t exist at all. So of course there will be people who will say we were too aggressive,” he said.

The superintendent said police would release bodycam footage of Monday’s arrests as soon as possible after formal charges were filed against those arrested.

Snelling rejected allegations by the National Lawyers Guild that two of those arrested had claimed they were simply in the wrong place at the wrong time.

“Sometimes it’s an indication of the decisions you make when you’re in the wrong place at the wrong time to commit criminal activity,” he said.

Since the DNC began, at least three complaints have been filed against police with the Civilian Office of Police Accountability, but details of those complaints were not made public during COPA’s investigation.