BANGKOK (AP) — Four people including a police major were killed in a shootout at an illegal gambling den in Thailand’s capital, an official said Tuesday.

Police who responded to a call about gunshots being fired at the venue in the southern part of Bangkok found the bodies of two women and two men, including police Maj. Wathaseth Sumniangprasert, according to Metropolitan Police Bureau commissioner Lt. Gen. Pakapong Pongpetra.

Gambling is generally illegal in Thailand, but small casinos with card games and gambling activities are fairly common in Bangkok, where their existence is generally an open secret.

Wathaseth was not on duty Monday night and was apparently taking part in the gambling, Pakapong said at a news conference Tuesday.

An initial investigation found that the other dead man had shot the police officer and then turned and fired wildly at the crowd, killing the two women. An unknown person then shot and killed the first gunman and fled before police could arrive from a nearby precinct, Pakapong siad.

A pistol and spent bullet shells were retrieved from the scene.

Pakapong said it seemed the gunman bore some grudge against the policeman.

Police are seeking the man who fled and also want to charge the owner of the site for hosting illegal gambling.