BERLIN (Reuters) - German police on Wednesday arrested a 19-year-old Algerian refugee who had fled a psychiatric facility earlier in the day yelling, “I’ll blow you up,” ending the latest in a string of incidents that have set the country’s nerves on edge.

German federal police arrested the asylum-seeker at the Bremen main train station after an hours-long manhunt that prompted the evacuation of a Bremen shopping center, according to police in the neighboring state of Lower Saxony.

They said an investigation was continuing.

Police said that when the man was in custody this past weekend for several thefts, he had sympathized with Islamic State and a gunman who killed nine people at a shopping center in Munich last Friday. But they said there was no further evidence of any ties.

Germany remains on edge after a spate of attacks that have claimed 15 lives since July 18, including those of four attackers. German officials have linked two of the incidents to Islamic State.

U.S. President Barack Obama spoke by phone with German Chancellor Angela Merkel on Wednesday to offer his condolences over the recent attacks in southern Germany, according to U.S. and German officials.

Obama offered Germany the U.S. government’s full support as investigations into the attacks proceed, the White House said in a statement.

Authorities had evacuated a shopping center in Bremen, about 40 km (25 miles) from the medical facility, after people identified a man who had been acting suspiciously as the missing patient.

A spokesman in Diepholz, where the man had been held by police over the weekend, said authorities took the incident seriously given the current situation in Germany, but emphasized that there was no evidence of an imminent attack.

“We only have these statements. We have no evidence of any concrete plans or even any ties to Islamic State,” he said.

The man was moved into psychiatric care after he tried to hurt himself multiple times and authorities determined he had consumed drugs and posed a possible danger to himself and others. He escaped from the facility early on Wednesday.

Police in Bremen said they were continuing to scour the shopping center for the man, who may have been carrying a backpack, and any objects he might have left behind.

There were no reports that he was carrying a weapon, they said.

Earlier, a suitcase exploded near a reception center for migrants in southern Germany, but authorities said the blast may have been caused by an aerosol can, and there was no sign of any explosives involved.