BALTIMORE (WJZ)—Fire marshals and police are on the hunt for a serial arsonist.

They gave Monique Griego an inside look into the investigation.

Cell phone video shows a massive apartment fire in Northeast Baltimore, ignited by a Molotov cocktail. Police say the firebomb was thrown into a window by a suspected serial arsonist who is choosing his targets at random.

“Anybody that could do this is a horrible person,” said Jamaal Simpson, whose home was damaged by the fire. “The fact that they would put innocent people, including children, in danger.”

But it may be just how blatant this arsonist was that helps police catch them.

“It puts a signature on it. I set this,” said Fire Marshal Ray O’Brocki.

O’Brocki says arson investigators are sifting through the rubble to find bits and pieces of evidence that tell a story of how and where a fire started. And if it’s intentional, the clues can come quickly.

“Anytime a suspect uses a device, there’s always something left of that device that screams arson. When they use gasoline it’s a heavy octane. It can survive the fire. You can still smell it,” O’Brocki said.

Pieces of the bottle used for firebomb on Lodestone Way were found in the debris.

O’Brocki says it’s already been handed over to CSI teams at the police department’s crime lab.

“They will presumably fingerprint the bottle, get DNA. All of this will be kept until an arrest is made,” O’Brocki said.

The fire destroyed 12 apartments but all 36 units were damaged, which means everyone who lived in one of these units was told they couldn’t come home.

“It’s one of those things you can’t prepare for,” Simpson said.

His family escaped unharmed, but seven of his neighbors were hospitalized. Others lost everything.

Simpson says residents won’t rest until the arsonist is caught.

“That’s somebody we don’t want running the streets,” Simpson said.

Residents displaced by the fire are staying in temporary housing until they can return home.

Police are asking anyone with information on this case to call them.