German authorities arrested Tuesday a 28-year-old Syrian in Hamburg on suspicion of planning a terrorist attack. The Federal Police, the Hamburg Regional Criminal Police, and the State Prosecutor's announced that it also suspected that the man was assisted by his 24-year-old brother, who lived in Kempten. According to the data, the two brothers planned an attack against civilian targets using an explosive belt that they made. The main suspect was said to have used the e-Bay platform to buy essential materials to make explosives and was encouraged by his brother to plan the crime. According to the data, he was arrested in the northern city of Hamburg based on a court-issued warrant for suspected terrorism financing offenses. Police searched many properties in Hamburg and Kempten on Tuesday morning as part of the campaign, seizing large amounts of evidence, including chemical substances. The operation included 250 police officers. Meanwhile, the German authorities suspect terrorist motives behind the stabbing attack last week at a gym in Duisburg, during which four people were injured. A spokesman for the Public Prosecutor in Dusseldorf confirmed that the authorities are considering an investigation with a Syrian suspect after the first analyses indicated a possible terrorist motive. According to the German TV station RTL, the authorities found pictures and video clips with an Islamic background on the suspect's mobile phone. Special police units arrested the suspect last Sunday at his home in Duisburg near the crime scene after the authorities received information from two of his acquaintances. According to the police, initial investigation thought that one of the injured, 21, was the main target of the attack. The Duisburg Public Prosecutor announced that none of the questioned victims knew the suspect. After the attack last Tuesday evening, a 26-year-old Syrian was taken into custody on charges of attempted murder. He is suspected of seriously injuring the four people with a knife.