Friend recounts victim's last moments before Houston explosion "I can hear a very loud hissing sound," the friend remembered.

A deadly explosion that left two people dead and sent shock waves throughout the city was felt by one of the victim's friends, just after they spoke on the phone.

Bobbie, a friend of one of the victims, told ABC Houston station KTRK that the two were on the phone when the victim arrived at the Watson Grinding and Manufacturing just before 4:30 a.m. Friday, when the blast occurred.

"He goes, 'Hey, something is not right.' I'm like why? And he's like, 'I'm here in the parking lot at my job and I just smell something really, really funny'. He goes, 'It smells like gas,'" Bobbie told the station.

She said he then told her another co-worker arrived and the two were going to check out the issue.

"He said, 'I can hear a very loud hissing sound,'" Bobbie said.

Not long after, she said she felt the explosion from her home about five miles away.

Bobbie said she hasn't been able to reach her friend since. She did not name which of the victims was her friend.

Authorities identified the two victims who were killed as Gerardo Castorena and Frank Flores, both employees at Watson Grinding and Manufacturing.

The manufacturing company issued a statement expressing its condolences to the families of the victims, but did not name the two employees who were killed.

"Our hearts go out to the families and businesses impacted by this incident and to our community," the statement read. "At this time, our immediate concern is the safety and well-being of everyone in the area and our employees."

The company was "working diligently" with federal, state and local authorities to investigate the accident, according to the statement.

It was not yet clear exactly what caused the explosion, but Houston Fire Chief Samuel Pena noted there was a leak coming from a 2,000-gallon tank of propylene.

Multiple homes and a nearby strip mall also sustained "significant damage" in the blast, which happened around 4:30 a.m. local time on Friday, Pena said at a press conference.

Houston Police Chief Art Acevedo said a multi-agency arson investigation has been launched. He made a point to note that there is no reason to believe it was terror-related or an intentional act.

It is protocol to conduct an investigation and it will look into whether all regulations had been properly followed prior to the explosion, according to Acevedo.

A temporary shelter was set up at 4703 Shadowdale Drive and at least 48 people were sheltering there, according to KTRK.

Acevedo asked for the public to consider offering help and donating to the families who had been affected.

"This is an area where it isn't the most affluent, so my thoughts are with all the individuals, whether they rent or own, that will be potentially displaced," Acevedo said.