Police were seen for hours throughout today and yesterday, January 18 and 19, on a Bury street.
Multiple force vehicles could be seen parked outside a house on Vernon Road, Greenmount.
Tactical vans arrived last night according to residents, with police stationed at the address until around 3pm today.
Officers could also reportedly be seen 'searching bins'.
There was no cordon in place.
One resident, who didn't want to be named, said: "There were three tactical vehicles, two police vans, we don't know what was going on, it's all been a bit worrying.
"Police were searching bins and the garden of the house, they have just been all over.
Read more: Police warning to residents after 2 burglaries and attempted burglary
Read more: Heartbroken mum's plea following son's death 15 years after 'unprovoked' attack
"We never see anything around here. I just hope everybody is okay and there hasn't been anything bad.
"Police left at around 3pm."
Another said: "There has been crime scene investigation vans since this morning and two tactical aid unit vans since last night, alongside the white unmarked car which is a police car too.
"Neighbours are worried and it’s caused some questions about what’s going on.
"There are very rarely police around here but this looks serious and has been rolling on since last night."
The resident added that, at around 3pm, they left after "20 hours" on scene.
One resident said: "They were here last night.
"There was a big black van, a tactical aid unit. It was unusual, you see sometimes a police car or ambulance, but that big van is something you would not usually see.
"It makes you wonder what is going on. I thought it odd that it was still there in the morning.
"There wasn't any tape, they weren't stopping you from going in."
Greater Manchester Police have been contacted for information.
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules here