Two people suffered minor injuries Monday morning in an explosion in a building at the University of New Brunswick in Fredericton.

Chemicals were involved in the explosion in the second floor laboratory, but no fire was reported, said city spokesperson Alycia Morehouse.

Assistant fire Chief Dave McKinley said those injured were researchers, not students.

The Enterprise Building #1, located at 2 Garland Court, houses tenants like research companies and business start-ups.

It will remain closed for the rest of the day, UNB officials said.

Gail Scott works in the Enterprise Building for Scene Sharp Technologies Inc. and said she heard "a noise like someone falling off a tall ladder, more than an explosion noise."

"It sounded like a crash sound. We just all looked at each other and said `That's not going to be pretty' and then just kept on working."

Within minutes sirens were in the air around the building as fire and ambulance crews arrived.

"As I watching the fire trucks everybody scurrying around, I saw two EMTs walking a couple of people down who looked quite hurt.," said Scott.

"There was a bandage on the side of their face. One guy was holding his hand up and it was all bandaged and stuff," she said. "There was blood. They were dropping blood as they were walking."

Marilyn Calhoun, who is a secretary in the Limerick Pulp and Paper research centre where the incident occurred, was in her office in the building when she heard the explosion.

"I just heard a big bang and there was a small — not a huge explosion — it didn't damage the building as you can see," said Calhoun.

"But I knew that there was something wrong, so I called 911."

Calhoun said there was blood visible at the scene of the explosion, but not much.

"You have to understand that if there is a glass, even a small glass flask that explodes, it's going to be a bit dangerous," she said.

McKinley indicated the injuries were of such a nature.

"We believe it's a small glass vessel where the people working on it received some minor injuries," said McKinley.

"We know that this building is working on things for the pulp and paper industry, so we're talking about fairly non-volatile chemicals," he said.

Calhoun did not know the chemicals involved.

"I'm a secretary. I'm not a chemical engineer," she said.

Firefighters evacuated the building on arrival. They received the call at 9:43 a.m.

By mid-day, fire crews were cleaning up the scene and McKinley indicated there was no continuing threat of explosion or danger.

One man, who was in the building, told fire officials there were five people in the room where the explosion occurred.

"We hear a big explosion and then we rush out of our office and see the guys running and a lot of blood here and we call 911," said the man to fire officials on the scene.

A crew trained in dealing with hazardous materials was initially called to the scene, but it was later decided their expertise was not needed.