The unexplained attack in the commuter town of Seongnam near the capital Seoul came days after another rare stabbing attack which killed one person and wounded three others.

The man was arrested at the scene, report says.

Portuguese police shot the alleged attacker after he refused to lay down a large knife and began to approach them.

The Royal Canadian Mounted Police say that Myles Sanderson was taken into custody near the town of Rosthern, Saskatchewan, about 100km southwest of where one of the bloodiest acts of mass violence in the country's history unfolded.

Police say that some of the victims may have been targeted, and some may be random.

The suspect in the stabbing, Hadi Matar of Fairview, New Jersey, pleaded not guilty to charges of attempted murder and assault at a court appearance on Saturday.

Police have yet to establish a motive for the attack.

His book agent says he will likely lose one eye, while the nerves in his arm were severed and his liver stabbed and damaged.

He suffered an apparent stab wound to the neck but his condition is not yet known.

The victim was taken to hospital after the knife attack on the road into the flashpoint neighbourhood of Sheikh Jarrah and was being treated for 'mild' injuries, police say.

David Amess, 69, the MP for Southend West in Essex, eastern England, was targeted at around midday at a meeting at the Belfairs Methodist Church in Leigh-on-Sea.

Advocating members of the public to mourn for the attacker is no different from supporting terrorism, Hong Kong police say.