Thirty-five people were arrested Friday in an "unlawful assembly" outside the San Diego Convention Center following GOP presidential candidate Donald Trump's first visit to San Diego, according to San Diego Police Department (SDPD).

SDPD had declared the gathering at the Trump Rally an "unlawful assembly" as of 4:30 p.m. Friday.

Thousands of protestors and Trump supporters began gathering since the morning near the San Diego Convention Center.

The crowd turned violent and officers moved in, wearing full riot gear and some carrying bags of tear gas.

SDPD Chief Zimmerman said there will be overnight police presence in the Gaslamp area.

Zimmerman said most of the crowd in downtown had been dispersed within an hour after dispersal order were given.

As of 6 p.m., protestors had blocked Harbor Drive between Downtown San Diego and Barrio Logan.

Police in full riot gear were marching down Harbor Drive towards Barrio Logan, attempting to push the crowd back. At least three people were detained on the bridge.

According to the legal dictionary, an unlawful assembly is "is a legal term to describe a group of people with the mutual intent of deliberate disturbance of the peace. If the group are about to start the act of disturbance, it is termed a rout; if the disturbance is commenced, it is then termed a riot."

SDPD Chief Shelley Zimmerman said around 4:30 p.m., several fights broke out in the crowd and protestors had started pushing and shoving.

According to a tweet by SDPD, as of 4:49 p.m., dispersal orders had been given and it was considered a misdeanor offense to stay in the area.

Officers with batons had slowly pushed the crowd back down to Harbor Drive. Multiple people were pepper sprayed.

5th arrest we've seen after Trump Rally at Convention Center. Police have cleared protestors from Gaslamp #NBC7 pic.twitter.com/7UD8n0phjJ — Omari Fleming (@OmariNBCSD) May 28, 2016

The San Diego MTS tweeted that all green line trains will turn around at the Convention Center until further notice.

But police and fire will remain in the Gaslamp area throughout the night.

According to SDPD, there was no property damage or injuries reported.

No other information was immediately available.