Hundreds of Danish police officers and soldiers launched a massive manhunt on Friday, suspending ferries and shutting down the Oresund Bridge connecting Denmark and Sweden, authorities said.
The Copenhagen police said in a statement that they were looking for a Sweden-registered Volvo carrying three people "connected to serious crimes".
Ferry traffic to Sweden and Germany was interrupted and the Great Baelt Bridge between the large Danish islands of Sjaelland and Fyn was also closed.
Both bridges were reopened around 1400 GMT as thousands of travellers were stranded in train stations, tunnels and on roads around Copenhagen.
Maritime traffic was slowly recovering and some trains linking western Denmark to Copenhagen skipped some stops to catch up, according to an AFP journalist at the scene.
"I spent 41 years in the Danish police, I have never seen such a big action taken before," Hans Jorgen Bonnichsen, the former head of operations at the Danish Security and Intelligence Service (PET), told local media.