YANGON, April 17 (Xinhua) -- Four people including a woman were killed with 42 others injured in traffic accidents on Myanmar's highway during the four-day long Thingyan water festival, a release from the Highway Police Force said Wednesday.

The traditional Thingyan water festival was celebrated on full swing across the country from April 13 to 16.

During the festival, 20 traffic accidents occurred on the Yangon-Mandalay highway.

"Almost all those road accidents were caused by the flat tire," a highway official told Xinhua.

During last year's water festival, hundreds of people were killed and injured in traffic accidents across the country.

The 587km-long highway, connecting the country's commercial city Yangon and the second largest city of Mandalay was opened to reduce the travel time between the two cities in December 2010.

Aiming to enhance better traffic safety along the highway, authorities have increased the number of road safety police to 16 police stations, providing 24-hour services for travelers since 2012.