BERKELEY, Calif. — Chanting “Not my president,” several hundred protesters streamed through the streets of Berkeley and Oakland in the predawn hours of Wednesday venting their anger at the election of Donald J. Trump as president. Demonstrations were also reported in Pittsburgh, Seattle and Portland, Ore.

The California Highway Patrol said that one protester, who was not identified, sustained major injuries after being hit by a car when protesters attempted to move onto a freeway.

The demonstration was one of the first visible signs of anger in the liberal and heavily Democratic San Francisco Bay Area after Mr. Trump’s surprising victory.

From Pennsylvania to California, Oregon and Washington State, hundreds of people hit the streets, according to reports by local news media and The Associated Press. In Oregon, dozens of people blocked traffic in downtown Portland and forced a delay for trains on two light rail lines. The crowd grew to about 300 people, according to local reports, including some who sat in the middle of the road to block traffic. The crowd of anti-Trump protesters burned American flags and chanted “That’s not my president.”