Following a chemical explosion, safety crews and firemen evacuated the Chemistry and Physical Sciences North buildings for over three hours Saturday.

As a result of the incident at 1:30 p.m., which produced deadly hydrochloric acid gas, CSOs and UCSB Police Dept. officers sealed off all entrances to the Chemistry building and the adjoining Physical Sciences North building, as well as the surrounding lawns, sidewalks and bike paths until 4:45 p.m.

The graduate students performing the experiment were working under Dr. Thomas Pettus, a chemistry professor and head researcher of the Pettus Organic Group, which aims to synthesize molecules useful in such fields as pharmaceuticals. Pettus was not present at the time.

The explosion happened during a routine procedure in which phosphorus oxychloride is boiled over a sodium wire to produce sodium hydroxide, which is in turn used in creating berkelic acid, a molecule found in abandoned pit mines that has shown preliminary promise as an anti-cancer agent.

Organic chemistry graduate student Luke Miller, whose lab partner was performing the experiment, said that the explosion was more dramatic than dangerous, filling the room with smoke but no fire.

“No one was hurt,” Miller said. “It just exploded. It sounded like someone threw a book down next to you really hard.”

Despite the use of a hood system, which is a type of containment chamber designed to suck harmful fumes out of the building, a small amount of smoke leaked out into the room, setting off fire alarms and prompting the Santa Barbara County Fire Dept. to send at least three engines as well as several special vehicles to deal with the chemicals.

Santa Barbara Fire Dept. Captain Mark Beeson said in these circumstances, the fire department evaluates the situation before the university calls private cleaning companies.

“We make sure that the situation is static,” Beeson said. “There was a very small amount [of gas] that was released. We went in and determined that there was no more gas in the air.”

Safety crews kept students and staff out of the buildings while the gas was filtered out of the room through the hood system. The fire department analyzed air quality with litmus paper and set up a camera in the affected lab to monitor the amount of smoke in the room.

No major cleanup was required as the broken glass and spilled liquid chemicals from the explosion were contained in the hood.

It is unclear what went wrong during the experiment, although bystanders speculated about impurities in the ingredients or an unexpected side reaction.

According to organic chemistry graduate student Jake Cha, who was in the lab building at the time of the explosion, this is a relatively common process that should not produce harmful gasses or explosions.

“It’s supposed to be relatively benign,” Cha said.