A letter that arrived at the Deutsche Bank headquarters in Frankfurt, Germany Wednesday was found to contain an explosive device after it passed through a mail room security X-ray.

The letter addressed to the bank's CEO Josef Ackermann and coming from the Central European Bank did not detonate and a powder inside it is now being tested by investigators to find out what kind of explosive it is.

Investigators, including those from the U.S. Federal Bureau of Investigation, also are trying to find out who sent the letter and the motive behind it.

The X-ray screening detected wires and pieces of metal inside the letter prompting the bank to alert the police. The police believe the purpose of the wires and metals is to ignite the explosive powder and cause bodily harm to the person who will open it, according to The Local.

Meanwhile, New York Deputy Police Commissioner Paul Browne said they have increased security around Manhattan's Deutsche Bank offices and warned Wall Street offices to be careful in handling packages and to increase mail room security, according to CNN.

Ackerman, 63, is set to step down as Deutsche Bank CEO in May 2012. He has been the bank's CEO since 2002.

Deutsche Bank CEO Josef Ackermann is the addressee of the letter bomb.