Authorities secured on Friday a suspicious device that was filled with nails and delivered to a pharmacy near a popular outdoor market in the German city of Potsdam. Police evacuated a large area of the city, which is located near the capital Berlin, in order to investigate the package. Peter Meyritz, a senior Potsdam police official, said the pharmacist alerted police on Friday afternoon after he opened the package and discovered wires, nails and batteries inside. Karl-Heinz Schroeter, interior minister of the state of Brandenburg, said the area would remain shut for now while police investigated whether any other similar packages had been delivered. “We are in the process of continuing our investigation ... It’s possible that additional packages were delivered here in the vicinity of the Christmas market,” Schroeter told reporters. “We want to ensure that no one is any danger.” He told reporters that several hundred grams of nails were found in a metal cylinder in the package, but said it was unclear if the device included any actual explosives. “We just don’t know at this point if this was a device that could have actually exploded or a fake or a test,” Schroeter said. "The evaluation and analysis is just beginning now," Schroeter said. "If it was really explosive or if it was a fake or a dummy, we will only know through further investigation." Experts used a robot to defuse the device using high-powered streams of water, officials said. Residents of the street were told to stay in the back of their homes while the procedure was carried out. There were no injuries reported in the evacuation or demolition of the package, which authorities said did not appear to include a fuse or other parts for a detonation. Potsdam police said it was too soon who may have been responsible. The package measured about 40 centimeters by 50 centimeters (16 inches by 20 inches) and was apparently delivered by a messenger service. Police said later on Twitter that the package included "a cylindrical object with cables, batteries and nails but at this point no ignition device has been found." Germany is on high alert for potential attacks nearly a year after an extremist hijacked a truck, killed its driver, and then rammed the vehicle into a Christmas market in central Berlin, killing 11 people there. Christmas markets opened across Germany on Monday at the start of the holiday season, fortified with security staff and concrete barriers to protect shoppers. Germany has around 2,600 such markets, filled with sparkling Christmas trees and wooden stalls serving candied nuts, sausages, mulled wine and handicrafts. Interior Minister Thomas de Maiziere said this week Germany had increased information-sharing between federal and state officials and taken other steps to increase security after a series of missteps in the Berlin case. A ministry spokesman said this week the risk of an attack in Europe and Germany is “continuously high”.