A street has been sealed off as police continue to search a property in Wigan amid reports that a bomb disposal unit was called to the scene.
Eyewitnesses posted photos on Twitter showing a bomb disposal van, and at least one street sealed off with a police cordon while a helicopter circled above.
Greater Manchester Police said officers had been at an address in the area since Wednesday evening, following the arrest of a man carrying a suspicious package.
A helicopter circled above the cordoned-off area, which stretched on to Wigan Lane, near the Wigan Royal Infirmary, while emergency vehicles filled the road, one witness said.
Wigan Council said Wigan Lane was closed between Mesnes Road and Central Parkway due to "a police incident", warning the public to avoid the area.
Tom Piper, who lives on Springfield Street, said the whole street had been evacuated.
The 25-year-old told the Press Association: "The police apparently turned up at 1.30am in the morning with guns and stormed the place. But I never heard it.
"Then they've been there all day, mainly just one or two police sat outside. Then about four or five-ish it looked like forensic people were there and then all of a sudden, about half-six, we all got told to evacuate."
Another witness said they had seen a bomb disposal squad unloading what appeared to be a specialist remote device to assist their search.