Counter-terrorism police in Britain have detained three men in connection to an explosion at a hospital Sunday in the city of Liverpool that killed one person and injured another.

Iran PressEurope: The British counter-terrorism police said the three men, whose ages ranged from 21 to 29, were detained in the Kensington area of the city.

Police were called to report a blast involving a taxi at Liverpool Women's Hospital on Sunday morning. Police said the explosion had not been declared a terrorist attack, but counter-terrorism police were leading the investigation and the men were detained under the Terrorism Act.

"So far we understand, the car involved was a taxi, which pulled up at the hospital shortly before the explosion occurred," Merseyside Police said in a statement. "Work is still going on to establish what has happened and could take some time before we are in a position to confirm anything."

The male passenger of the car died and the driver was being treated for non-life-threatening injuries. Police said they were "keeping an open mind" about what caused the explosion.

The Liverpool Women's Hospital said it immediately restricted visiting access until further notice and diverted patients to other hospitals "where possible."

Fire services said they extinguished the car fire rapidly, and a person had left the car before the fire "developed to the extent that it did."