Two young teenage siblings, a boy and a girl, and a middle-aged man were found killed in Härnösand in northern Sweden on Tuesday evening.

A third suspect was arrested at luchtime on Wednesday in Umeå. Police had earlier issued a warrant for his arrest. He revealed when he boarded the boat that he was headed for Germany.

The arrest was confirmed by deputy chief prosecutor Bertil Månsson of the Sundsvall Public Prosecution Office, who is the leader of a preliminary investigation, Expressen.se reported.

The man who was arrested is in his 20s. According to Allehanda.se, the man is not known for any past crimes.

Earlier, police arrested a man in his 60s on Tuesday and a second man, also in his 60s, overnight on suspicion of murder. One of the men was taken in for questioning from his home in a small locality near Härnösand.

Previously, police said that the men were arrested on “reasonable suspicion” of committing the murders, a technical term meaning that more evidence would be required to press a case against the suspects.

A press conference about the investigation will be held at Sundsvall police station on Wednesday afternoon.

Earlier, the first two men who were arrested denied having anything to do with the killings.

“He is admitting nothing. That is to say, he denies the allegations,” Hans Björner of Västernorrland police said previously about the first man.

An anonymous tip sent early on Tuesday evening to SOS Alarm said that there were three lifeless bodies in the villa in central Härnösand. Police found two teenagers and a middle-aged man dead on arrival at the scene.

“It was concluded straight away that the people were dead and that they had been subjected to violence. We cannot yet say how they were killed, but all the indications are that they were killed just prior to the alarm call,” Björner said earlier on Wednesday.

Police would not comment on the relationship between the two men and the victims. However, they are not known to police for previous crimes.

Björner said police have not yet been able to establish a motive for the attack.

“We have a number of possible theories that we are working on, but no clear picture on the motive,” Björner told news agency TT.

The first man was arrested in the vicinity of the house where the three bodies were found.

At Härnösand’s Kiörningskolan, students grieved the loss of two of their schoolmates.

Classes were canceled and students gathered in groups to talk about the tragedy.

School staff said nothing about the family had given them cause for concern:

“Nothing. They were children that we were very happy to have and we had good cooperation with the mother,” said Bert Olsson, president of the Solen municipal school management area, to which the murdered children’s school belonged.

The house has been cordoned off and police technicians have begun combing the property for clues. The work was broken off overnight and resumed on Wednesday morning as part of an investigation involving 20 to 30 officers.

Following an arrest, the prosecutor has three days to come to a decision over whether the suspect should be remanded into custody, according to Björner.