FORT BEND COUNTY, Texas -

No one answered at a home in the 15000 block of Oak View Trail in Fort Bend County mid-morning Thursday.

Neighbors said early in the morning they heard a big boom when the front door was knocked open as investigators served a search warrant and arrested three people.

"I thought it was an explosion," said one neighbor.  "He was a quiet neighbor.  Didn't cause any problems.  The motorcycles.  We would hear a lot of noise with that.  Other than that,  I don't think any of the neighbors were surprised."

The US Postal Inspector said the search warrant was aimed at a major online distributor of synthetic drugs.  The spokesperson says contraband was seized during the search. 

Another source told Local 2 that money orders were also seized. 

Investigators from the US Postal Inspector, the Drug Enforcement Administration and the Missouri City Police seized three motorcycles plus a Bentley, a Mercedes and a Cadillac Escalade.

Investigators say this is an ongoing investigation and others could face charges.  They said charges in this case could include first degree felonies.