Wilderswil (Switzerland) (AFP) - Five people were shot dead and a man was seriously injured Monday as two unrelated shooting dramas rocked normally placid Switzerland.

A man is suspected of shooting one woman to death in an apartment in the northern city of Basel before killing another woman and critically injuring a man in a nearby flat, the regional public prosecutor's office said.

Riot police surrounded the apartment of the suspected killer in the evening and arrested him, the statement said, without providing a motive or further details.

The killings came just hours after three bodies were discovered in the Alps town of Wilderswil in what appeared to be a murder-suicide.

One woman and two men had been killed in the shooting near the train station, police said.

"Initial elements indicate that this is a relationship-related crime, and the suspected shooter is one of the two men died," Bern police said in a statement.

Media reported that two men and one woman, all Portuguese citizens, had been killed in a jealousy drama.

According to the Tages Anzeiger daily, the gunman had killed his ex-wife and her new husband, before turning his gun on himself.

An acquaintance of the woman told the newspaper that her ex-husband had rung her doorbell and when she opened the door, shot her in the head.

When her new husband, whom she married two months ago, arrived at the scene, he was shot down too.

"She was finally happy again, remarried and with a new job," her boss at the laundromat where she worked told the Blick daily.

The gunman had also reportedly tried to get into the house in what may have been a bid to kill his three children, aged seven to 21, but his eldest daughter slammed the door on him.

The man, who had reportedly been harassing and threatening his ex-wife for some time before the shooting, then took his own life.

Police said the gun used in the shooting had been found.

The shooting dramas shook usually tranquil Switzerland, which is relatively unaccustomed to gun-related crimes.

This despite having one of the highest rates of gun ownership in the world, since all healthy Swiss men aged between 18 and 34 are obliged to do military service and all are issued with assault rifles or pistols which they are supposed to keep at home.