Three people were hurt in a series of crashes Tuesday morning on Interstate 79 in southern Butler County, state police said.

The wrecks, blamed on slippery road conditions or driver error, or both, closed a portion of the highway for several hours.

The first accident happened about 7:35 a.m. when Jill K. Allhouse, 28, of West View, Allegheny County, lost control of her northbound car on I-79 in Jackson Township.

The vehicle traveled across the grass median and onto the opposing lanes, hitting the front of a car driven by Brenda R. Russo, 42, of Harmony, which was in the left southbound lane, police said.

Allhouse’s vehicle continued into the right lane and collided with a car driven by Alexandria Schwartzmier, 27, of Harmony.

Russo and Allhouse were taken to Allegheny General Hospital in Pittsburgh with moderate and minor injuries, respectively. Russo was not wearing a seat belt.

Police said Allhouse, who was wearing a seat belt, was cited for driving too fast for conditions.

Harmony and Zelienople volunteer firefighters assisted police. Emergency crews remained at the scene until 10:45 a.m.

Less than an hour after the first accident, police said, a pickup truck driven by Roger J. Reiser, 46, of Fombell, Beaver County, crossed into the path of a Peterbilt truck just before 8:30 p.m. in Lancaster Township.

Reiser, who was wearing a seat belt, suffered minor injuries. The accident closed the highway for about 90 minutes. Zelienople volunteer firefighters assisted police at the scene.

Stephen P. Nazaruk, 54, of Houtzdale, Clearfield County, was driving the heavy truck.

Minutes later, police said, Noel M. Stranger, 29, of Greenville, Mercer County, lost control of his northbound sport utility vehicle on the highway in Jackson Township.

Stranger’s SUV about 8:40 a.m. traveled off the west berm, crossed the grass median separating the north and south lanes and continued into the southbound lanes from the east berm.

The car struck the left front end of the SUV, driven by Susan J. Cravener, 48, of Portersville, which was in the right lane. Police noted that Cravener at the time was stopped for a traffic back up caused by one of the earlier accidents.