Witnesses in Somalia's capital say the militant group al-Shabab has publicly executed two teenagers by firing squad.

The executions took place Monday in front of hundreds of Mogadishu residents.  

One of the teens executed was a 15-year-old boy, accused of sexually molesting another boy, age 9.  The other teen, said to be 18 years old, was accused of spying for the Somali transitional government.

Al-Shabab is trying to overthrow the Western-backed government and impose a harshly conservative form of Islamic law across Somalia.  

Last month, the group executed two teenage girls it accused of spying for  the government.  Back in April, it publicly executed an accused murderer and chopped off the hand of an alleged thief.

Some information for this report was provided by AP.