36 people were killed and 26 injured in a horrific train crash in Indonesia on Saturday, according to officials.

One train that was on its way from Semarang to Jakarta was hit from behind by a second train, that was also headed to Jakarta, from Surabaya. The train that was struck from behind was stationary when the crash occurred, and many people were crushed by the impact.

Xinhua News quoted one witness to the aftermath of the wreck as saying “I heard the crash that sounded like an explosion. I quickly came to the crash scene and helped to bring out the victims from inside the trains. I saw many bodies with their heads off and some others loose their body parts.”

Susilo Bambang Yudhoyono, President of the Republic of Indonesia, conveyed his condolences to the victim’s families and said a formal investigation would be conducted. A preliminary investigation has indicated the crash was caused by human error.

Travelers aboard the train reported loud noises and hard shaking during the crash. One passenger noted how the lights went off once the crash took place.

The crash occurred on one of Indonesia’s larger islands, Java. Java has the most active railway system in Indonesia. Rail passenger services range from executive class coaches with air conditioning, to non-air conditioned economy coaches with bench seating. Two organizations, one private, one government, run the trains in Java. It has not been reported which one owns the trains that were involved in today’s crash.