(CNN)More than 200 people were injured in Malaysia on Monday when two trains collided in the capital Kuala Lumpur, the state-run Bernama news agency reported.
The accident occurred at 8:45 p.m. local time when one of the trains, which was going on a test run and had only one driver, collided with a train carrying passengers.
Both trains, which are operated by Prasarana Malaysia Berhad, were traveling at 40 km (approximately 25 miles) per hour when they collided in a tunnel between the Kampung Baru and KLCC stations, state media said.
Some 166 people sustained minor injuries and were sent to nearby hospitals for treatment, including Kuala Lumpur Hospital. Forty-seven passengers were severely injured, state media added.
Videos and photos posted on social media showed several passengers bleeding and broken glass panels inside the trains.
Dang Wangi District Police chief ACP Mohamad Zainal Abdullah said that the train carrying passengers was heading from KLCC station -- an underground tunnel close to the Petronas Twin Towers -- to the Gombak station at one end of the line. The empty train was going from Kampung Baru station to the Gombak station, Abdullah said, according to state media.
Malaysia's Prime Minister Tan Sri Muhyiddin Yassin has called for a full investigation to discover the cause of the accident.
"I take this accident seriously and have instructed the Transport Ministry and Prasarana Malaysia Berhad to conduct a full investigation," he said, Bernama reported.
Transport Minister Wee Ka Siong said the collision was the first major accident in the metro system's 23 years of operation, and he pledged a thorough investigation, Reuters reported.
The 88-storey Petronas Twin Towers are the tallest twin towers in the world.