About 50 firefighters tackled a severe fire at what is thought to be a factory which makes Christmas decorations.
Crews spent the night at the Alma Street, Heath Town, in Wolverhampton, where a fire broke out on Monday evening.
Nearby residents were warned to keep windows and doors shut because of large amounts of smoke.
At one stage, the building was "100% involved in fire", West Midlands Fire Service said on Twitter.
Adam Lawrence, who saw the fire said: "I saw loads of smoke, flames.
"It was quite a big fire."
The incident was scaled down from 10 pumps to four at about 02:00 BST, some five hours after the fire started.
Crews remained at the scene on Tuesday afternoon.
VIDEO UPDATE: Incident at Alma Street, Heath Town, Wolverhampton— West Midlands Fire (@WestMidsFire) April 3, 2018
Crews still in attendance, although incident has been scaled down. Investigations into the cause continue. pic.twitter.com/LRfeBrZ5eU
Investigations into the cause of the fire are continuing.