The East Grand Boulevard roadway at the Corona (91) Freeway will remain closed and construction work will halt until Monday for officials to investigate the ramp's partial collapse that left workers injured Friday.
Nine workers were injured, three critically, late Friday night when the temporary support beams of the freeway ramp partially collapsed, officials said.
The collapse was reported about 11 p.m., according to the Riverside County Transportation Commission.
Part of an on-ramp was being lowered into place when the jacking operation failed, causing the bridge deck to drop about 16 inches and strike the temporary wooden support beams. Those beams hit workers and caused injury, according to a news release from the RCTC.
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Kassandra Juarez, who was in the area at the time, said the collapse sounded "like a big boom. Like an earthquake - the ground started shaking."
The injured workers were taken to a hospital. One was released and three were hospitalized in critical condition.
"Our goal at this job is to our work safely so everyone goes home at the end of the day," said Jan Bohn, project manager. "That's a big deal for all of us. We failed yesterday."
The workers are affiliated with Atkinson Walsh Construction Joint Venture, the prime contractor, officials said.
Engineers inspected the bridge Saturday morning. Officials said the incident did not affect the 91 Freeway.
The on-ramp construction was a part of the 91 Project, which will add regular and toll express lanes, and direct lane connections to the 15 Freeway. The project is expected to be completed in 2017.
East Grand Boulevard was closed between 3rd and Joy streets, according to the Corona Police Department.
On Saturday, all lanes on the 91 Freeway were open, according to the California Highway Patrol.
Jason Kandel and Jamie Bankson contributed to this report.