Police in Copenhagen said they were looking for a Sweden-registered vehicle with three people on board.

Danish police on Friday cut off the eastern island of Zealand, where the capital Copenhagen sits, from the rest of the country as well as from neighbouring Germany and Sweden as they launched a nationwide manhunt over a suspected kidnapping.

Bridges from Denmark’s Zealand to the central island of Funen and to Sweden, as well as ferry crossings to Germany and Sweden, were closed, causing major traffic jams near bridges to Sweden and to the mainland.

Danish police said in a statement that they “are searching for a black Swedish-registered Volvo V90 with registration number ZBP 546”.

“The vehicle probably contains three persons linked to a serious crime,” the statement said.

Calle Persson, a press spokesman for the Swedish police, told Swedish newspaper Aftonbladet the “scene of the crime” was Malmo airport in Sweden.

Television footage showed cars being checked as they drove through roadblocks at the Oresund bridge to Sweden, causing traffic jams up to 15km long, according to the Danish Road Directorate.

The car is registered with First Rent A Car in Stockholm. Police warned the public not to approach the individuals in the vehicle.

Denmark’s TV2 said a police helicopter and a search with canine squads was spotted on the highway near Roskilde, 25km west of Copenhagen.

Copenhagen airport remained open during the manhunt, according to its website.

Copenhagen police later said all bridges and ferry crossings had been reopened, but heavily armed police officers were screening cars at bridges and ferries across the country.

Though the bridges and ferry crossings have opened, police “have personnel standing at every connection to make manual checks”, Copenhagen police spokesperson Riad Tolba was quoted as saying by UK newspaper The Telegraph.