ANTIOCH (CBS SF) — An injury accident involving an overturned tractor-trailer in Antioch Tuesday morning closed the westbound Highway 4 connector ramp to Highway 160 for 11 hours, according to authorities.

The 511.org Twitter account first posted about the accident on the State Route 4 westbound connector shortly after 6 a.m. Tuesday. CHP later issued a severe traffic alert due to the crash.

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Five hours later, authorities confirmed that the work to clear the accident and reopen the connector ramp was ongoing.

Drivers are advised to expect delays and to use alternate routes to avoid the area. Caltrans estimated time the roadway would reopen at 1 p.m. That estimate was later pushed back to 4 p.m., but the connector did not reopen until closer to 5 p.m.

There was a second accident near Pittsburgh when an overturned cement truck blocked ramps to and from eastbound state Highway 4, according to the California Highway Patrol.

The crash was reported at about 10:55 a.m. near the on-ramp from Bailey Road to eastbound Highway 4.

An ambulance responded to the scene but CHP officials did not immediately say if the cement truck driver was injured.

The on-ramp and off-ramp reopened shortly after 2:30 p.m., authorities said.

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The accident comes after the California Highway Patrol confirmed two fatal crashes Monday on State Route 4 near the Alhambra Avenue off-ramp in Martinez.

The victims have since been identified by the county coroner’s office.

The first crash was reported shortly before 10:30 a.m. on westbound Highway 4 east of McEwen Road. According to the California Highway Patrol, a Ford Ranger truck went down an embankment and the driver, identified as Alexis Perez Morales, 24, of Brentwood, was not wearing a seatbelt and was ejected from the vehicle.

Perez Morales was taken to a hospital and succumbed to his injuries there.

The second crash was reported shortly before 6:30 p.m. near the Alhambra Avenue off-ramp from westbound Highway 4, according to the CHP.

The driver, identified as 18-year-old Concord resident Luis Ceja Jr., lost control and his car went off the highway and hit a tree, CHP officials said. No other details about the crash were immediately available.

Anyone with information about either crash is asked to call the CHP’s Contra Costa-area office at (925) 646-4980.

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