The shooting is believed to have occurred around 3:30 p.m. local time. A man wearing body armor was spotted near the mall's Macy's and food court, according to the Oregonian. Witnesses say they heard between 20 and 60 gunshots.
In addition to the male gunman, two are dead and one is injured, according to the sheriff's department. Initial reports on CNN indicated the shooter used an AR-15, the same semi-automatic rifle that James Holmes was suspected of using in Aurora, Colorado, in July.
A witness told local station KOIN that the gunman was wearing all black and a white Halloween mask. Others have reported the mask was a "V for Vendetta" or Guy Fawkes mask. Another witness said it was a white hockey mask.
In a press conference, authorities said they believe there was just one gunman. It's unclear whether he took his own life or was killed. A witness told Portland's KATU she saw a man lying on the ground outside Forever 21 with a gun next to him.
The mall has been closed.
Some people believed to be witnesses tweeted updates while the shooter was at large:
The city or Portland's mayor has also issued a statement:
A statement from Oregon Governor John Kitzhaber:
My thoughts and prayers are with the victims and their families. I appreciate the work of the first responders and their quick reaction to this tragic shooting. Oregon State Police Superintendent Rich Evans is on the scene. I have directed State Police to make any and all necessary resources available to local law enforcement.
Check back here for updates.