shoot-out in a suburb of the northern Italian city of Milan on Friday, a security source told Reuters.
Italy's interior minister was to hold a news conference at 10.45 a.m. (0445 ET) the ministry said.
A short video posted on the website of Italian magazine Panorama suggested the shooting happened before dawn, with police gathered around a cordoned-off area in the dark.
The report was one of several conflicting accounts on the whereabouts of the 24-year-old Tunisian Anis Amri.
A man matching his description was seen in Aalborg in northern Denmark, the Danish police tweeted on Friday, saying people should keep away from the area as it had an ongoing operation there.
Amri was also was caught on camera by police on a regular stake-out at a mosque in Berlin's Moabit district early on Tuesday a few hours after the attack, Germany's rbb public broadcaster reported.
Amri was not a suspect at that time, and on Thursday morning, when police raided the mosque, they could not find him, rbb said.
German investigators had said they believed Amri was still lying low in Berlin because he is probably wounded and would not want to attract attention, Der Tagesspiegel, reported citing security sources.
In the early hours of Friday morning, special forces arrested two men suspected of planning an attack on a shopping mall in the city of OberhausenIn in the western state of North Rhine-Westphalia, police said in a statement.
The men - two brothers from Kosovo, aged 28 and 31 - were arrested in the city of Duisburg on information from security sources, they said.
A police spokesman said there was no connection between the Duisburg arrests and the Amri case, which has been claimed by Islamic State.
Amri had been identified by security agencies as a potential threat and had his application for asylum rejected, but authorities had not managed to deport him because of missing identity documents.