Update, 3.45pm: Lincolnshire Fire and Rescue have confirmed that the cause of the smoke was an electrical fault with an air ventilation system.
A spokesperson explained that a motor within the unit had burnt out, causing smoke to be pumped through the building.
The motor was taken out by crews and made safe. There are no ongoing investigations.
Lincolnshire Fire and Rescue crews blocked off a city centre street due to an incident at a block of high-rise apartments.
Fire crews attended the scene at the Witham Wharf multi-storey apartment building on Brayford Street, east of Brayford Pool, where a number of residents have reported that they could smell smoke inside the building.
A Lincolnite reporter at the scene has said people were evacuated from the building and that fire alarms had been sounding for about an hour.
A Lincolnshire Fire and Rescue spokesperson said: “We attended reports of smoke at the Brayford multi-storey accommodation at 1.24pm.
“Three crews attended from Lincoln South and Lincoln North.
“Fire crews are still on site in an effort to determine the cause.”
A student who lives on the fourth floor of the building said there was a significant amount of smoke on the third floor of the building as he was leaving.
Another resident said they believed smoke may have been coming from the bottom floor of the building.
Officers placed cones on the entrance to the road and at least four fire engines are in attendance.
Police incident signs were placed at the junction with Brayford Wharf East.
A hydraulic crane pulled up outside the NCP multi-storey car park building at around 1.30pm on Tuesday, July 4. Water pumps are also being used.
Western Power vans also arrived on scene at around 2.15pm.
Drivers were advised to avoid the area.