(CNN) -- Connecticut authorities arrested a man who they said was interested in committing a mass shooting, had weapons and tactical gear, and made his intentions known on Facebook.

Brandon Wagshol, 22, was detained Thursday after a tip from a citizen that he was trying to buy large capacity rifle magazines from out of state, the FBI and the Norwalk Police Department said.

Wagshol has been charged with four counts of illegal possession of large capacity magazines, and is being held on a $250,000 bond. He is scheduled to appear in court September 6. CNN has reached out to the prosecutor and defense attorney.

How the investigation started

The FBI and Norwalk Police Department started investigating after the tip.

They discovered the suspect was trying to build his own rifle and had posted on Facebook expressing an interest in committing a mass shooting, according to a statement from the police and the FBI.

It did not provide details on what his post said.

When authorities executed a search warrant at his home, they found numerous weapons, including a handgun, a rifle, a rifle scope with laser, numerous rounds of ammunition, body armor, ballistic helmet and other tactical gear, police said.

While some of the weapons were registered to his father, he had access to them, authorities said.

"We continue to urge the public to please remain alert and to report to law enforcement any suspicious activity that is observed either in person or online," said Brian Turner, FBI special agent in charge . "With our local partners we gather, share and act upon threat information as it comes to our attention."