Danish police have arrested a 22-year-old ethnic Dane in connection with a deadly shooting at a Copenhagen shopping mall.
Police chief Soeren Thomassen said the motive was unclear, but that he could not rule out an "act of terrorism".
Mr Thomassen said several people were killed in Sunday's shooting, adding it was too early to provide exact figures.
Eyewitnesses have spoken of panic among shoppers as gunfire rang out inside the Field's mall in the south of the city.
Emilie Jeppesen told Jyllands-Posten newspaper: "You didn't know what was happening. Suddenly there was just chaos everywhere."
Another witness, Mahdi Al-Wazni, told TV2 that the shooter had carried a "hunting rifle".
Speaking at a news conference on Sunday evening, Mr Thomassen said it was too early to say how many people had been harmed in the attack.
But he told reporters that there was no indication that other attackers were involved and urged shop owners to preserve any video surveillance footage they may have.
Field's is said to be the largest shopping centre in Denmark, with over 140 shops and restaurants. The multi-storey mall is located on the outskirts of Copenhagen, just across from a subway line that connects to the city centre.
A concert British singer Harry Styles was due to perform at a venue less than a mile from the scene and has now been cancelled.
Writing on Snapchat, Styles said: "My team and I pray for everyone involved in the Copenhagen shopping mall shooting. I am shocked. Love H."
Shortly after the shooting, the Danish royal family announced that a reception due to being hosted by Crown Prince Frederik had been cancelled. The event had been organised to celebrate Denmark hosting the first three stages of the Tour de France.
Denmark last saw a major terror event in 2015, when two people were killed and six police officers were injured during an attack on a cultural centre and a synagogue in Copenhagen.
The gunman was later killed in a shootout with police.
