London ? They had diverse backgrounds, coming from countries around the globe, but all shared youth and worked in medicine. They also had a common goal, authorities suspect: to bring havoc and death to the heart of Britain.

The eight people held Tuesday in the failed car bombing plot include one doctor from Iraq and two from India. There is a physician from Lebanon and a Jordanian doctor and his medical assistant wife. Another doctor and a medical student are thought to be from the Middle East.

All employees of the United Kingdom’s National Health Service, some worked together as colleagues at hospitals in England and Scotland, and experts and officials say the evidence points to the plot being hatched after they met in Britain, rather than overseas.

“To think that these guys were a sleeper cell and somehow were able to plan this operation from the different places they were, and then orchestrate being hired by the NHS so they could get to the UK, then get jobs in the same area – I think that’s a planning impossibility,” said Bob Ayres, a former U.S. intelligence officer now at London’s Chatham House think tank.

“A much more likely scenario is they were here together, they discovered that they shared some common ideology, and then they decided to act on this while here in the UK,” he said.

No one has been charged in the plot in which two car bombs failed to explode in central London early Friday and two men rammed a Jeep Cherokee loaded with gas cylinders into the entrance of Glasgow International Airport and set it on fire the following day.

Investigators believe the main plotters have been rounded up, including one in custody in Australia, though others involved on the periphery, including at least one British-born suspect, were still being hunted, a British government security official said, speaking on condition of anonymity because of the sensitivity of the details.

In the current case, Muhammad Haneef, a 27-year-old doctor from India arrested late Monday in Brisbane, Australia, worked in 2005 at Halton Hospital near Liverpool in northern England, hospital spokesman Mark Shone said.

Another Indian doctor, 26, arrested late Saturday in Liverpool, worked at the same hospital, Shone confirmed, but refused to divulge his name.

A third suspect, Mohammed Jamil Asha, a 26-year-old doctor from Jordan of Palestinian heritage, was arrested Saturday with his wife, Marwa Asha, 27, who was identified in British media reports as a medical assistant. He worked at North Staffordshire Hospital, near the Midlands town of Newcastle-under-Lyme.

A doctor at Royal Alexandra Hospital in Glasgow, who refused to give his name, said he recognized Asha as a doctor who kept an office there – the same hospital where another suspect, Bilal Talal Abdul Samad Abdulla, worked.

According to friends of Abdulla’s family in Iraq, the 27-year-old doctor came to Britain after graduating from medical school in Baghdad. He was a passenger in the Jeep Cherokee that rammed into the Glasgow airport.

The Jeep’s driver – identified by staff at Royal Alexandra Hospital as a Lebanese doctor named Khalid Ahmed – was in critical condition at that hospital from burns suffered in the attack. Police would not confirm his identity.

Investigators believe the same men who parked the explosives-laden cars in London may have also driven the blazing SUV in Glasgow, the British security official said.

The final two suspects, ages 25 and 28, were arrested by police Sunday at Royal Alexandra Hospital. Staff said one was a medical student and the other a junior doctor, without giving their names. British media said they were from Saudi Arabia, but police refused to comment.