Huddersfield and Sheffield terror arrests after armed raids
Residents heard "loud bangs" when armed officers swooped on two addresses in terror raids.
The properties, in Huddersfield and Sheffield, were searched by counter-terror officers after police received a tip-off.
Explosions heard by eyewitnesses in both locations were caused by police accessing properties, officers said.
Two men, aged 24 and 29, were held in Huddersfield and Sheffield on suspicion of terror offences.
The BBC understands the arrests are Islamist-related.
Police said the raids were not linked to the recent Manchester Arena attack.
'An almighty explosion'
In Sheffield, residents at the Daisy Spring Works apartment block in Kelham Island told the BBC a door was blown off at a second floor property.
Nick Meeks, who lives on the same floor as the flat which was raided, said he heard an "almighty explosion".
"I stuck my head out of the door and there were fully-armed police pointing guns down the hallway towards me screaming and shouting at me to get back in the flat," he said.
A resident on Rudding Street in Crosland Moor, Huddersfield, who did not wish to be named, said at one point his "house shook".
He said: "I heard a loud bang that sounded like a really big explosion, I thought it was a bomb.
"I ran outside and saw about 30 police and armed officers. People on the street have been kept inside their houses."
The North East Counter Terrorism Unit said the two arrested men, both from Huddersfield, were being held on suspicion of offences under Section 5 of the Terrorism Act.