A man suffered serious injuries after he jumped or fell from a 30-foot bridge in Newport Beach on Thursday morning, authorities said.

Nobody witnessed the man plummet from the Arches Bridge over West Coast Highway at Newport Boulevard about 6:30 a.m., Newport Beach Fire Department Battalion Chief Todd Knipp said.

First responders found the man on the sidewalk, where bystanders were tending to him, Knipp said.

He was transported to Western Medical Center in Santa Ana in critical condition, according to fire officials.

— Jeremiah Dobruck

Twitter: @jeremiahdobruck