At least 20 are dead after a military officer opened fire in the city of Nakhon Ratchasima in Thailand. The junior officer, Jakraphanth Thomma, 32, reportedly killed his commanding officer at a military installation before making off with weapons and a large vehicle, then making his way into the city to continue his rampage. He remains at large and his motive is unknown.

After killing his CO at the Sutham Phithak military camp, Thomma also reportedly killed another soldier and a woman, 63, before leaving the base. He opened fire at several locations in the city before arriving at the Terminal 21 shopping complex. He is currently believed to be held up in this location.

“We don’t know why he did this,” Thai Defense Ministry spokesman Kongcheep Tantrawanit said in a statement to Al Jazeera. “It appears he went mad.”

Local authorities have closed off the complex and are attempting to locate Thomma. Witnesses have reported hearing gunfire from inside the building.

“The gunman used a machine gun and shot innocent victims, resulting in many injured and dead," government spokesperson Krissana Pattanacharoen said in a statement to the press.

Video footage from Terminal 21 shows Thomma exiting his vehicle and entering the complex with a rifle. Other footage captured a fire outside the shopping center which was likely started when a bullet hit a gas canister.

Nakhon Ratchasima has a population of over 166,000 and is located roughly 160 miles northeast of the capital city of Bangkok.

Animated map shows location of a mass shooting in northeastern Thailand Animated map shows location of a mass shooting in northeastern Thailand Photo: AFP /