People were evacuated from their homes last night after West Midlands Police found a suspect device during raids which resulted in 21 arrests.
Farm Road, in Rowley Regis, Sandwell, and neighbouring streets were sealed off as a bomb disposal team dealt with the suspect package, which was discovered to be a black box containing a stopwatch and wires.
There was no controlled explosion and the box was taken away for further examination. A man was arrested at the property.
Armed officers were involved in the operation in which 15 men and six women aged 13 to 35 were detained and a firearm also recovered.
Police said it was part of a long-standing investigation into gun crime and none of the arrests were under the Terrorism Act but senior officers said they were keeping an open mind and investigations were continuing.
It came less than 24 hours after Birmingham city centre was paralysed when more than 20,000 revellers were evacuated from pubs and clubs and four suspect devices blown up in controlled explosions. None were found to be explosive.
Yesterday, at least two more controlled explosions were carried out in Birmingham, in Kingstanding and Bartley Green. Again, both devices were later deemed to be harmless.
The Rowley Regis residents were allowed to return to their properties at 10pm, more than six hours after the initial scare. One, Paul Fletcher, said police officers wearing breathing apparatus and carrying machine guns had forced their way into the house.
?It looked like they used tear gas,? he said. ?They went in with Alsatians, then came out with the man?s wife and his daughter and then brought him out in handcuffs.?
Meanwhile, as West Midlands Chief Constable Paul Scott-Lee defended the decision to carry out a mass evacuation of Birmingham city centre on Saturday night, a security expert raised the spectre of a second terror group operating in Britain.
Sean McGough said there was the possibility another group, not linked to last Thursday?s London outrage, prompted the West Midlands force to clear pubs and clubs on the busiest night of the week.
It is believed police received specific threats which, combined with calls from members of the public about suspicious packages, forced them to act.
Mr Scott-Lee yesterday insisted there had been a ?real and significant? threat to lives.
?I can tell you that, bearing in mind the current world climate, the information we received posed a real threat to the lives of people in the city centre,? he said. ?I believe this threat was significant for me to authorise this evacuation.
?The packages were incidental to the threat we were responding to.?
Mr Scott-Lee would not go into details about the specific threat. A security source also told The Birmingham Post Saturday night?s actions were ?a local issue? and not connected to the London bombings.
However, Mr McGough, a specialist in terrorism at Birmingham University, said suggestions about a specific threat raised the possibility that a group unconnected to the London bombings may be in the region.
?The obvious option is that there is one other group operating in Britain besides that cell which acted in London, which poses a terrorist threat. Obviously that possibility is worrying,? he said.
?Police have real and genuine intelligence of a credible threat to the city. They have gone out and searched the area and found packages that were suspicious. People are mistakenly thinking this was a normal alert where people have rung up about suspicious packages and the police have come out to investigate.?
The drama on Saturday began just before 8pm when police issued a public warning calling for vigilance and called on premises in the city centre to carry out searches for suspicious packages. At 8.40pm police decided to evacuate the Broad Street, Mailbox and Chinatown areas of the city in light of fresh information, bringing thousands of people onto the streets.
Birmingham Chamber of Commerce and Industry spokesman John Lamb backed the police measure despite its estimated seven-figure cost to the city?s economy.
He said: ?Obviously we are disappointed for the traders. I think 20,000 people would have spent a considerable amount of money in the bars, restaurants and hotels.
?It?s impossible to put an accurate figure on it, but I would not think #1 million is too wide of the mark, at least.?
Coun Mike Whitby, leader of Birmingham City Council, said thanked the public ?for their understanding and quick action in safely leaving the city?. He added that 600 people forced to leave hotels in the restricted areas were put up at Aston University and Lady-wood Arts and Leisure Centre. However, not all those involved in the evacuation praised the police?s actions. Peter Hetherington, who was in Birmingham for a family party, criticised the lack of information from the officers on the ground.
He said: ?My daughter was close to one of the London bombs on Thursday and she said the police were magnificent on that day.
?The apparent lack of police strategy to deal with people after the bars, restaurants and hotels were emptied looks pretty poor by comparison.?