BANGKOK, April 20 (Xinhua) -- A pickup truck plunged into roadside ditch and overturned in eastern Thailand's Sa Kaeo province late Thursday, killing six and injuring three Thai teenagers, Thailand's Department of Disaster Prevention and Mitigation (DDPM) said on Friday.

The accident happened on Chanthaburi-Sa Kaeo road at Wang Nam Yen District of the province at about 10:00 p.m. local time on Thursday.

Local media reported that the teenagers went to attend a water-splashing celebration in Sa Kaeo Province and were on their way back home when the accident occurred.

The teenagers were driving at 170km/hr, reports said, which might be the cause of the accident, though the exact cause is still under investigation.

According to the World Health Organization, Thailand's road traffic fatality rate is 36.2 per 100,000 with an annual estimate of over 24,000 deaths or 66 deaths every day.