Police in St. Louis are searching for a gunman who shot and wounded a 27-year-old woman on Interstate 70 on Tuesday afternoon.

Authorities released a photograph of the suspect, who is seen with his torso sticking out of the front passenger side window of a silver Mercedes-Benz sedan while holding what appears to be an assault weapon.

The woman told police that at around 4:15pm on Tuesday, the man opened fire, hitting her in the back and arm.

Police in St. Louis released a photograph showing a suspected gunman who shot a female motorist on Interstate 70 on Tuesday afternoon

Police are asking for the public's help in tracking down the suspected gunman

She told police that she does not know the suspect.

The woman was rushed to hospital, where she is listed in critical but stable condition.

Authorities asked anyone with information to contact CrimeStoppers online or at 1-866-371-8477. Tipsters can remain anonymous and may be eligible for a reward.