A police operation was underway early on Wednesday around Strasbourg cathedral near where a gunman killed three people and wounded a dozen others on Tuesday evening.

A Reuters reporter saw police officers securing a zone close to the site of the northern city’s Christmas market.

The gunman, who is believed to have been injured by security forces on Tuesday according to French media reports, is on the run and France has raised its security threat to the highest alert level and strengthened border controls.

Police identified the suspect as Strasbourg-born Cherif Chekatt, 29, who was known to the intelligence services as a potential security risk. On the opposite side of the Rhine river German police also tightened border controls, officials said.

The European Parliament, which is sitting in Strasbourg this week, was put into lockdown after the attack.