COPENHAGEN - Police in western Denmark's Jutland peninsula have been kept busy on Tuesday as bomb threats were separately delivered to three places in one day, all of which turned out to be false alarms, local media reported.

The first threat was a letter that was sent to Aarhus University, in middle Jutland, just after 9 am (0700 GMT), according to the Danish newspaper Jyllands-Posten. Local police quickly responded and determined that it was a hoax.

Two hours later, a man called the southern Jutland police and made a bomb threat against a local school, which was then evacuated in an orderly manner.

Bomb-sniffing dogs were sent to the school and police shortly arrested a local 36-year-old man, according to a police press release.

The third bomb threat was aimed at Aalborg University Hospital in northern Jutland.

According to the police, the threat was delivered by phone just before 12:30 pm (1030 GMT) by a 33-year-old woman. Police quickly determined that there was no threat as the woman is "mentally unbalanced" and had made similar threats before.

Bomb threats are not unusual in the Scandinavian country, although it is well known for its social stability and peacefulness.

According to the newspaper, the national police have registered 51 cases of bomb threats from July 2013 to November 2014.

The country is on high alert nowadays after a twin shooting attacks by a gunman has left two people dead in Copenhagen in mid February.

Last month, police in Copenhagen said a series of notes threatening a new and more extensive terror attack had been found in the same Copenhagen district where the gunman opened fire on a free speech debate.

After the shootings, five men have been arrested for allegedly helping the gunman, a 22-year-old Dane of Palestinian origin, obtain and get rid of the weapons that he used in the attacks.