A 23-year-old German man is in custody after falsely claiming to have a bomb inside a suitcase he was trying to bring into the U.S. Embassy, police said Friday.

The incident began around 7:30 a.m. when the man was turned away at the door of the downtown embassy near the landmark Brandenburg Gate by security personnel, police spokesman Jens Berger said.

Police identified the man as a German, but the U.S. Embassy said in a statement that he presented security personnel with an American passport, saying he wanted to renew it. He then punched a guard when he was told he'd have to go to a different location for passport renewal, the embassy said.

As he was being arrested by Berlin police at the scene, Berger said he told them there was a bomb in his suitcase that was in front of the entrance.

The area was quickly cleared and a police robot was brought in to open the bag, but found only "personal items" like clothes, police said.

Few details about the man were immediately available, but Berger said "there are many indications he is psychologically disturbed."

The investigation is continuing, he said.