Manama, Bahrain (CNN) -- Clashes broke out in Bahrain on Friday as authorities tried to prevent thousands of opposition supporters converging on a mosque to hear a sermon from the kingdom's most prominent Shia cleric, Sheikh Isa Qassim.
The unrest followed a series of bombings in the capital, Manama, earlier this week, and the government's decision to strip some 31 opposition activists of their citizenship.
Amid the unrest Friday, a teenage boy was knocked over by a car and killed as he crossed a busy road in the area.
Sixteen-year-old Ali Abbas Radhi had been detained by police, according to witnesses and his family, and then escaped. They said he was hit by the car as he was pursued.
The Ministry of Interior said Radhi was killed as he tried to cross the road, but made no reference to his being arrested.
The Bahraini opposition is made up largely of the kingdom's Shiite majority, which has long complained that it is marginalized under the rule of the Sunni al Khalifa dynasty. As the Arab Spring erupted last year, opposition groups twice occupied the island's famous Pearl Roundabout, until protestors were dispersed in a security crackdown in March 2011.
The opposition had called prayers Friday to support Sheikh Qassim, who has come under attack in pro-government media for meeting the Iranian consul in Bahrain. Authorities summoned the Iranian charge d'affaires in Manama last month to complain about the meeting.
A large number of police had sealed off access to the mosque in the village of Diraz. Witnesses say many worshippers abandoned their cars and tried to reach the mosque on foot. Police fired tear gas to prevent people from reaching Diraz, according to witnesses.
The Ministry of Interior in a statement said the roads had been closed to prevent "vandals from outside the area" from gathering, after receiving information that protests were planned.
Earlier this week, authorities said the 31 people stripped of their Bahraini nationality had harmed state security. They included three former members of parliament and several opposition figures.
A leading cleric, Ayatollah Hussein Al-Najati, also lost his Bahraini nationality. Ayatollah Al-Najati is the representative in Bahrain of Iraq's Grand Ayatollah Ali al Sistani, whose teachings are widely followed by the island's Shiite communities.
In his sermon Friday, Ayatollah Qassim criticized both the move to deprive Bahrainis of their nationality and bomb explosions this week in Manama, which killed two Indian workers. He also called for only peaceful forms of protest.
Attempts at political dialogue between the government and opposition parties have made little progress, and there's been an uptick in violence in recent weeks.
Condemning the bombings, the U.S. State Department said this week that violence had "claimed the lives of protesters, of security forces, of innocent bystanders."
State Department spokeswoman Victoria Nuland said the violence "undercuts the process of national reconciliation that we have strongly been urging on Bahrainis of all stripes." On Friday Nuland welcomed a declaration of non-violence by six opposition parties.
But Ayham Kamel, an analyst with the Eurasia Group, said that "Shia hardliners that condone the use of violence, such as Haq and the 14 February movement, are likely to use the wave of attacks to reinforce their rising popularity."
Since anti-government protests began in February 2011, more than 100 civilians and at least six police officers have been killed in sporadic violence.