Investigations to determine the cause of a fire that shut a major road for hours are still ongoing.

A fire broke out on the edge of Bushey Heath first thing yesterday (April 6) and multiple fire crews rushed to the scene.

The road in Sparrows Herne was closed by police for most of the day, only reopening at around 5pm.

Now Hertfordshire Fire and Rescue reveals that they were called to the scene at 5.52am on April 6, alerting police about the incident just minutes later at 6am.

Houses faced severe damage from the fire (Photo: Nathan Louis)

Houses faced 'severe damage' from the fire (Photo: Nathan Louis)

On arrival, firefighters found that a fire on the first floor of a terraced house, which spread into the roof space and to two neighbouring properties.

In total, there were thirteen fire engines called across Hertfordshire – including an aerial ladder and a command support unit – to help tackle the fire.

It is said that the fire was extinguished by 8.15am, but crews remained on site after being concerned that there could still be people in the buildings.

Houses faced severe damage from the fire (Photo: Nathan Louis)

Houses faced 'severe damage' from the fire (Photo: Nathan Louis)

However, after a search everyone was accounted for safely, with some of the emergency services spotted leaving the scene at around 10.30am.

A police cordon and some fire crews remained in place until around 5pm.

A spokesperson from Hertfordshire County Council, speaking on behalf of the fire and rescue team, said: “This was a difficult operation for fire crews as the fire caused extensive damage to the buildings, including a partial collapse of the roof and internal floors.

“Structural engineers are assessing the building.”

Police closed off the road until around 5pm (Photo: Nathan Louis)

Police closed off the road until around 5pm (Photo: Nathan Louis)

From the outside it appeared serious damage was caused to rooftops both at the front and back of one house, with shattered windows, with similar damage to the other two properties in the same complex.

One eyewitness, Lisa Lorton, recalled after being woken up by the noise, she looked outside and saw smoke.

She stated it appeared the houses had ‘severe damage’.

Houses faced severe damage from the fire (Photo: Lisa Lorton)

Houses faced 'severe damage' from the fire (Photo: Lisa Lorton)

Currently it is unclear what the cause of the fire was, and investigations are ongoing.

Yesterday, police at the scene said they were treating the area as a crime scene while enquiries are carried out to determine the cause of the fire.

It is understood that the fire and rescue team currently believe the fire started accidentally.