PHOENIX -- Another wrong-way driver caused two wrecks on Interstate 17 and investigators believe impairment might be a factor.
It happened at about 10:15 p.m. Wednesday. The first report of the wrong-way driver put him in the southbound lanes of I-17 near Seventh Avenue.
Although a Department of Public Safety officer was in position to ram the suspect's vehicle and stop him near McDowell Road, the driver veered around him and kept going.
The wrong-way driver, a man in his 60s, went on to sideswipe a car carrying two people before slamming head-on into a second vehicle.
Four people, including the suspect, were hurt in the two crashes. All of them suffered serious injuries.
"Impairment may be a factor in both crashes," DPS Officer Carrick Cook said in an email to media outlets. As it stands, pending lab results from the DPS Crime Lab, the driver of the wrong-way vehicle is facing several aggravated assault charges along with various other criminal charges. In the event that someone should pass away as a result of the crash, those charges could be upgraded to homicide."
DPS has not released any information about the suspect.
Seven wrong-way crashes since April
Wednesday's incident is the latest in a series of recent crashes involving wrong-way drivers -- seven since April, three in one week alone. Most of those wrecks involved fatalities.
One in particular made national headlines. A man who was in the country illegally hit and killed an off-duty Mesa police officer on May 12.
The driver went for about 35 miles on multiple freeways before plowing into Sgt. Brandon Mendoza, who was on his way home from work. More than 30 people called 911 to report the wrong-way driver, but DPS officers were not able to get to him in time.
Both Mendoza and the suspect, Raul Silva Corona, were killed. The Maricopa County Medical Examiner's Officer later determined that Corona was drunk. Corona's sons said they tried to stop him from driving that night.
Mendoza's mother is speaking out after writing a letter to President Barack Obama.
"I am furious that the federal government allowed this criminal to stay in this country and kill my son!" Mary Ann Mendoza wrote in that letter
Appearing on "The O'Reilly Factor," she said Corona should have been deported for previous brushes with the law, including drunk driving. She believes her son would be alive today had that happened.
Solving the problem
Arizona officials are trying to figure out how to curb wrong-way accidents on state highways.
In June, the Arizona Department of Transportation installed new "Do Not Enter" and "Wrong Way" signs at six freeway interchanges as a test. In addition to being significantly larger, the signs also are lower, putting them in drivers' eyelines.
Crews also placed reflective pavement markers in the shape of large arrows pointing the proper direction on exit ramps.
If the "enhanced signage" proves effective, ADOT will make changes at other locations throughout the Valley metro area and the state.
According to ADOT, there are more than 100 traffic interchanges on the Phoenix-area freeway system and more than 475 interchanges along the rest of the state highway system.
DPS officers say wrong-way driver side-swiped one car, crashed head-on into another on I-17 near Thomas. 4 people in serious condition— Jill Galus (@JillGalus) July 31, 2014
The Associated Press contributed to this story.