A Bahraini court jailed three people for life and sentenced another to 15 years on Thursday for attacking a bus during a protest in a Shia village.
Sunni-ruled Bahrain has been shaken by unrest since it quelled a month-long Shia-led uprising demanding reforms five years ago.
Quoted by the official BNA news agency, prosecutor Ahmed al-Hammadi said the four had attacked the bus during a protest that blocked a highway near the Shia village of Sanabis in November 2014.
The four intercepted the approaching bus during the protest, set it alight and opened fire on its driver "in an attempt to kill him and those aboard," Hammadi said.
No casualties were reported in the incident and it was unclear why the protesters may have targeted the bus, which the statement said belonged to a private company in Bahrain.
Tiny but strategic Bahrain, which is connected to regional Sunni powerhouse Saudi Arabia by a causeway, lies across the Gulf from Shia Iran and is home to the US Fifth Fleet.
Despite the crackdown on the 2011 uprising, protesters continue to clash frequently with police in Shia villages outside the capital Manama.