
The explosion occurred at 8:15 pm, police said.
Bomb disposal officials rushed to the scene to check the explosive device and police from Chana Songkram station closed the section of the road in front of the theatre, which is opposite from the National Museum.
The bomb experts could not yet identify the type of explosive device. They said the device was hidden inside a garbage bin in front of the theatre.
The two injured women were identified as Chanpen Wutthi-ekpaibul and Kanchana Booncheep.
They were slightly hit by shrapnel at their left arm. They were taken to receive treatment at the first aid treatment tent of the Army, which is nearby.
First Army Area Commander Lt Gen Apirat Kongsompong said the explosion might be an effort to create disturbance like the explosion in front of the old Government Lottery Office two months ago.
Apirat said the explosion spot was outside the area around the Grand Palace that tightly monitored by troops.
He said the explosion might be caused by a giant firecracker.
Deputy Prime Minister and Defense Minister Gen Prawit Wongsuwan said he has been informed of the incident but it has not yet been confirmed whether the explosion was caused by a bomb.