Terror raids in Huddersfield and Sheffield are not related to the ongoing investigation into the Manchester Arena bomb attack, police have said.
Two men have been arrested in the Yorkshire operations, one at a property in the Crosland Moor area of Huddersfield and another in the Kelham Island area of Sheffield.
People living close to both locations reported being startled by large bangs and then seeing scores of police, many armed.
The North East Counter Terrorism Unit (CTU) moved to reassure the public, saying the loud noises were part of police operations to gain entry to addresses.
People living around a block of flats between Dun Street and Cornish Street, close to Sheffield's Inner Ring Road, said the bang went off at about 5:30pm on Thursday.
One man who lived in the block said he saw a second-floor flat's door had been blown off.
Others said they saw armed plain-clothed officers in the triangular courtyard in the centre of the modern block.
On Thursday night, cordons on the streets surrounding the property were being lifted, although a number of police officers continued to guard the block, which is opposite the Shalesmoor tram stop, as a searches continued.
Similar scenes were reported in Huddersfield, where a large number of armed police were deployed in the Ellison Street area of the town.
The CTU spokeswoman said the arrested men, aged 24 and 29, are both from Huddersfield and were detained on suspicion of offences under Section 5 of the Terrorism Act.
She said they were detained at separate locations in Huddersfield and Sheffield.
"There are no connections to the recent incident and investigation in Manchester," the spokeswoman said.
"The operation is based on recently received intelligence.
"The public may have heard loud bangs at the time that police entered the property.
"We would like to reassure you that this was part of the method of entry to gain access to the property."