BERLIN — The police in Germany blocked off parts of the historic old city of Dresden on Saturday morning and evacuated a shopping center there because of a standoff with an armed assailant in which two hostages were taken.

The police said they believed that the suspect, whom they identified as a 40-year-old German citizen, had shot his mother before moving on to the center of the city. The man’s mother, who was 62, was found dead in a multifamily dwelling in a residential area earlier in the morning.

The police said after detaining the man that the two hostages were unhurt.

The city’s traditional Christmas market was not allowed to open on Saturday morning because of the volatile situation.