5:45 p.m. UPDATE: The pro-Trump event at Schrunk Plaza and the anti-Trump event at City Hall are both over now with few people remaining. Police report four arrests at 4th and Morrison. Future arrests may still occur pending investigation, they said. IDs of those detained have been recorded.
The Oregonian/Oregon Live reported that its reporters were detained by police.
4:30 p.m. UPDATE: Police have divided crowds gathered at SW 4th Avenue and Morrison Street. Many in the crowd have their hands up in the air. Several have been detained by police using flex cuffs.
Several businesses, including Sephora, have boarded up their windows.
Portland police in full riot gear are trying to shut down a rally in Portland on Sunday afternoon after violence broke out.
Police said bricks, glass and other projectiles were being thrown at them.
Police are using stun grenades and tear gas to close Chapman Square. Shortly after 4 p.m. police announced they were also shutting down Lownsdale Square, across the street from Chapman.
Trump supporters are now dispersing into other rallies. Law enforcement from Homeland Security are also on scene.
KATU-TV is reporting that the pro-Trump rally is still being held as a peace rally in front of City Hall.
Protestors in black masks are confronting police officers, KATU said.
Earlier, Portland Police made numerous tweets showing a wide variety of weapons confiscated.
Police, over loudspeakers, are telling crowds gathering in the streets that they are engaging in illegal assembly and must disperse.
This is a developing news story and it will be updated.