The Royal Logistic Corps Bomb Disposal team from Catterick was also on the scene, although a spokesman said they could find no explosive device.
This morning, all that remained was a small tar-like stain. However, police have declined to comment further as to what their investigations had revealed.
In a previous statement, released on the day of the explosion, a police spokesman said: "Humberside Police received a call from a member of the public who reported having heard some sort of small explosion.
"Police and fire attended and located a spot where a small fire was burning out.
"Nobody was believed to have been in the area at the time and there were no injuries reported."
Despite the explosion happening in the early hours of the morning, residents said there was no sign of a police cordon until several hours later.
Hedon town councillors were asked by the police to direct pedestrians around the area on Thursday morning.
One 78-year-old woman, who wished to remain anonymous, said: "The explosion woke me up. It was so loud, it left me shaking.
"It certainly didn't sound like a firework, but I'm not sure what it was."
Anyone with information should contact Humberside Police on 101 referring to log 36 of June 6.
