A knifeman stabbed a woman to death in front of terrified bystanders in Barcelona in what authorities believe was a random street killing.

A photo of the alleged attacker brandishing the weapon he used on his victim emerged overnight as police confirmed they had made an arrest.

The fatal stabbing took place in broad daylight yesterday morning in Esplugues de Llobregat – an area in the southwest of the city that sits around two miles west of the Camp Nou stadium, home to FC Barcelona – at around 11am. 

Police are still trying to establish whether the attacker knew his victim, whose age and nationality have not yet been revealed.

They have confirmed there was no romantic relationship between the pair that they were aware of, and well-placed sources said they were focusing on the theory that it was a random stabbing.

The woman, described locally as ‘young’ and in one unconfirmed report as being of possible Asian origin, was stabbed in the throat, chest and stomach.

A man aged 50 was also injured in the incident after intervening and suffered wounds to his arm, but his condition is not serious.

The suspected killer, who was wearing jeans and a hoodie and carrying a large black rucksack, was arrested around midday in Barcelona’s Les Corts neighbourhood, which sits next to the Esplugues de Llobregat area. 

Esplugues de Llobregat Town Hall said in an initial statement: ‘We deeply regret the violent death of a person in the town and extend our condolences to their family and loved ones.

‘The council condemns all forms of violence and expresses its concern over these serious incidents, which affect community life and public safety.

‘The alleged perpetrator has already been arrested by the Mossos d’Esquadra regional police force.

‘From the outset, the Council has been coordinating with the Mossos d’Esquadra, the force leading the investigation, and the Esplugues Local Police, and is offering all necessary institutional cooperation to help clarify the facts.’

In a second statement, it confirmed it had decreed two days of official mourning, which started at midnight today.

The Mossos d’Esquadra regional police force said in its own statement in the aftermath of the fatal stabbing: ‘Officers have arrested a man as the suspected author of a violent death committed this afternoon in Esplugues de Llobregat in the province of Barcelona.

‘At around 11am, the 112 emergency number received a report that a man had injured a woman and fled the scene.

‘Police and the Emergency Medical Service (SEM) attended the scene, but were unable to save her life.

‘The alleged perpetrator was later located and arrested.’

Footage from the scene shows a forensic tent erected, concealing the body from members of the public.

Terrorism has been ruled out as a motive.