BERLIN, Germany — Half a dozen armed police formed a circle around the rubbish bin while one of their colleagues gingerly prodded open the canvas bag that had been dumped carelessly on the bin’s rim.

The police phalanx steered people away from the bag's vicinity at Berlin’s central train station while the officer checked the contents of the bag. It was just rubbish left by a busy traveller. A false alarm.

“If I wasn’t worried before, I am now for sure,” said Carola Bohnert, 26, who was watching the event unfold on Monday night while waiting for a train to Hamburg. “They’re taking it very seriously.”

Like all German transport hubs and tourist attractions, the central station has gone about its business under the watchful eyes of heavily armed police since last Wednesday, when Interior Minister Thomas de Maiziere announced the government had “concrete indications” that a major attack was being planned.

A short distance from the station, the historic Reichstag building, which houses Germany’s federal parliament, had earlier in the day been closed to visitors. News reports in Germany said it was a potential target for an armed siege modelled on the 2008 Mumbai attacks by Lashkar-e-Taiba, the Pakistan-based Islamic militants.

The mood in Berlin is, if not panicked, then at least decidedly twitchy. It certainly is a contrast to the reaction in early October when the U.S. State Department issued a travel alert warning of a heightened threat of terrorism across Europe. Then, Germans reacted with a collective shrug, dismissing it as an American overreaction.

This time is different. There is an unavoidable feeling that the German government is deeply concerned, perhaps even holding its breath. The Reichstag on Monday night was sealed off with red and white barriers and police officers gruffly turned away people wanting to pass through the surrounding area, even by bicycle.

“We’re not so much concerned as disappointed because we wanted to go inside the Reichstag today,” said Jan, a 28-year-old Briton on vacation in Berlin. “Actually my mum is concerned. She was telling me not to visit any crowded places. But yes it does seem pretty serious.”

De Maiziere, a man of calm demeanor, has been praised for the level-headed way he has conveyed information about the threat. The fact that he was obviously annoyed seven weeks ago by what he described as the “alarmist” Europe-wide alerts means that the grave tone he is now adopting carries all the more weight.

His remark that Germany was “presently dealing with a new situation” sounded ominous, especially as it was followed by reports that police vacation time was being cancelled. The head of the Federal Police, Matthias Seeger, said that on a scale one to 10, the present threat level was nine.

This sense of concern has filtered through to the public. Several times in recent days, authorities have evacuated trains or station platforms in major cities because of bomb fears. In one instance, last Friday, they cleared part of Hannover’s central station because a commuter reported what was described as a “suspicious plastic bag.”

“I do feel a little bit nervous,” said Sylke Kleindorfer, 61, at the Berlin central station, patting a hand against her chest. “I heard there was supposed to be something today. The station does seem quieter than it usually is.”

According to the news magazine Der Spiegel, the state of alert began when a German jihadist who had travelled to the border region between Pakistan and Afghanistan for training, but become disillusioned, called the Federal Criminal Police (BKA) offering information about planned attacks in return for amnesty. One plan that had been discussed, he said, was for a small gang of armed jihadists to storm the Reichstag, take hostages and create a bloodbath.

Two of the attackers were already in Germany, he said, and four more were to follow. The information could be unreliable. But it dovetailed with details passed to the German authorities by the FBI, which said a little-known Indian Shiite group called “Saif” or “sword” had sent operatives to the Waziristan border region to prepare for an attack on German soil.

The warnings come at a terrible time for Germans as they prepare for their popular Christmas markets, where large crowds gather as at no other time of the year.

Of course, not everyone is worried by the latest warnings. On the streets, men generally didn’t acknowledge even a niggling fear. But compared with seven weeks ago, the typical response when GlobalPost asked people about their fears had shifted. Before, the prevailing attitude was that authorities in the U.S. were overreacting. This time, naysayers were more likely to offer fatalistic responses rather than outright dismissals.

“What happens happens. There’s no point in worrying about it because the chances of it affecting me are small and, anyway, there’s nothing I can do about it,” said Michael Siebeck, 51, who was at the train station. “But I know it will feel different after the first attack here.”