THREE policemen were killed and at least seven others injured when terrorists detonated a bomb in a Bahraini village yesterday.
An improvised explosive device (IED) was triggered as police came under attack following a funeral procession in Daih at around 5pm.
Bahrain's Interior Ministry said it was one of three blasts in Daih, although two resulted in no injuries.
A fourth bomb was discovered and defused.
Yesterday's was the biggest death toll suffered by security forces in a single attack since anti-government radicals began a campaign of violence following the unrest in 2011.
Among those killed was a UAE officer who was part of the GCC Peninsula Shield Force, Bahrain's Interior Ministry said.
The bombs went off after rioters pelted stones and Molotov cocktails at police following a procession for Jaffar Al Durazi, an inmate with sickle cell anaemia who died in hospital last Wednesday.
He was in police custody after being arrested in connection with a plot to smuggle detonators and explosives into Bahrain by boat.
The IED was detonated remotely as police dispersed armed rioters in Daih.
"The initial investigation indicates that terrorists planted the bomb near a lamp-post on Budaiya Highway," the Interior Ministry said.
"The device was remotely detonated while police were securing the roads and restoring order."
It said security checkpoints were set up in the area to support the work of investigators, while the Public Prosecution has been notified.
"The Interior Ministry will conduct a thorough investigation to find and arrest those responsible for the killings of the policemen," it said.
Coinciding with the funeral procession, saboteurs had caused traffic disruption from noon by blocking roads in Jidhafs, Daih, Tashan, Khamis and adjoining areas.
Several police checkpoints were set up during the day, but as police dispersed rioters, the blast occurred.
The Emirati officer has been identified as First Lieutenant Tariq Al Shehi.
The UAE Interior Ministry said in a statement carried by the WAM state news agency that he died along with two members of the Bahraini police force "while performing his national duty of maintaining order".
The two other policemen killed were named as Ammar Abdulrahman and Mohammed Arsalan, although their identities were not confirmed by authorities.
Yesterday's tool takes the number of policemen killed since February, 2011 to 13, while more than 2,500 have been hurt in clashes with violent anti-government rioters.
A graphic picture circulated online hours after yesterday's tragedy showed two riot policemen lying in a pool of blood as their colleagues tried to revive them.
Riot police were also pictured standing near the body of a seriously injured officer.
A radical opposition group calling itself the Popular Resistance Brigades claimed responsibility for the attack, which happened a day after the government released a report stating explosive devices used by rioters in Bahrain were the same as those employed by insurgents in Afghanistan and Iraq.
The attack sparked an angry and emotional response on social media, with Bahrainis calling for an end to terrorism and describing it as a "dark day" in the country's history.
Riot police maintained a tight security presence in the area of the blast last night and security checkpoints were set up, with only Daih residents reportedly allowed to enter the village.
One restaurant employee, who heard the bomb go off, said many people left after the blast.
"Most people in the area left their homes and went elsewhere because the situation is going to be tense," he said.
Armoured police vehicles were also present at the entrance to Jidhafs as they dealt with rioters who continued to pelt stones and Molotov cocktails at security forces throughout the evening.
There was also an increased police presence in Sanabis.