A clash with demonstrators Saturday left conservative writer Andy Ngo with a brain hemorrhage, he wrote in an opinion piece in the Wall Street Journal on Tuesday.

Ngo — who described himself as a gay journalist of color — said he could have up to six months of memory loss from the hemorrhage, after he was beaten at an event for antifa, a left-leaning militant group. He said he also suffered a ripped earlobe.

He described being punched and kicked by about a dozen people dressed all in black, which he said was typical clothing for members of antifa.

Three people were arrested Saturday as protesters from the left and right held separate demonstrations and then converged at Pioneer Courthouse Square, which led to some instances of violence. None of the arrests were connected to the attack on Ngo.

Portland police and city Mayor Ted Wheeler have received national criticism of how the demonstrations were handled after videos and photos of Ngo being attacked went viral.

Ngo wrote that he was threatened, cursed at, blocked from walking around and followed by left-wing protesters. He said police didn’t intervene.

When milkshakes were dumped on Ngo, he said, he immediately reported it to police. In the first incident, he said, officers told him they wouldn’t approach the suspect, who was still in sight, because it could incite the crowd.

Ngo said a mob hit him in the face and the back of his head until he let go of his camera, which someone took. More “milkshakes, eggs, rocks, silly string and possibly pepper spray” were dumped on him.

Portland police Lt. Tina Jones, bureau spokeswoman, said police were “actively looking into that incident.''

Jones said she doesn’t know where officers were at the time Ngo was assaulted.

Officers during Saturday’s protest were dealing with rapidly changing, dynamic demonstrations from at least three different groups and were intent on keeping the groups separated, while "doing what they could to facilitate free speech, she said.

When problems occur, "we respond as quickly as we can,'' Jones said.

Speaking generally and not specific to Ngo’s complaints, Jones added, "We don’t have the resources to be individual bodyguards."

If Ngo has specific complaints that police are not following their policies, Jones said she’d encourage him to file a complaint with the city’s police oversight division called the Independent Police Review.

The Oregonian/OregonLive reporter Maxine Bernstein contributed to this report.

-- Christina Morales; cmorales@oregonian.com; 503-221-5771; @Christina_M18

Visit subscription.oregonlive.com/newsletters to get Oregonian/OregonLive journalism delivered to your email inbox.