A man who crashed his car into a San Jose Walmart Sunday morning and began randomly beating people with a metal club was likely under the influence of methamphetamine, police said.

The incident occurred just after 11 a.m., as a man who has not yet been named crashed his red Oldsmobile Cutlas into two other cars in the parking lot of a Walmart store, then cruised along a walkway near the front doors before plowing through the entrance.

The driver kept on the gas for another 30 feet until the car finally came to a stop atop a beer display, at which point the driver exited and began assaulting people nearby with a metal club, according to The Mercury News.

Police said four people were wounded, including one seriously. One of the injured people is a Walmart cashier, and sources told NBC Bay Area that another is a pregnant woman.

It was not initially clear why the man erupted in such a shocking manner, but police later told KTVU-TV that he appeared to be under the influence of methamphetamine, the street version of a a highly addictive prescription stimulant that can cause extreme euphoria and aggression at high doses.

This video is from CBS San Francisco, aired Sunday, March 31, 2013.