Hackers identifying themselves with the Antisec movement have attacked the site of a company that sells equipment to US law enforcers such as the police.
A message posted over New York Ironwork's homepage said it was a "tribute to Jeremy Hammond".
Mr Hammond has been accused of being involved in an attack on the think tank Stratfor last year and was arrested in Chicago on Monday.
This marks the second breach explicitly linked to the FBI's swoop.
The bureau also charged five other men with computer crimes, including Lulzsec's "leader" Hector Xavier Monsegur - known as Sabu - who helped officers with the crackdown after pleading guilty to 12 criminal acts.
Earlier this week Antisec attacked the website of the Spanish firm Panda Security, accusing it of helping police arrest other members of Anonymous, the name given to the wider hacktivist campaign. The firm denied the allegation.
Those responsible for the latest attack signalled that they intended to continue their campaign.
"We'll fight till the end," the message said.
"To the FBI... you have our logs, we have all those PMs [private messages] and private chats u don't want to make public. Antisec is still alive and well. We refuse to let some... snitch divert us from our path in life."
New York Ironworks sells gun lasers, pepper spray holders and tactical clothing.
Its Facebook page says it "has spent well over a decade earning the respect of police officers in and around New York".
A spokesman for the company told the BBC that he had no comment on the matter.
TheCyber War News blogalso revealed that Antisec had leaked the source code from Symantec's 2006 version of its Norton anti-virus software.
An accompanying statement made reference to the recent arrests.
Symantec had said thatit expected the move, having previously confirmed the theft. It said customers who had more recent versions of the software were not at risk.
Joss Wright, a research fellow at the Oxford Internet Institute, said it was not yet clear what the long-term consequences of the Lulzsec and Antisec crackdown would be.
"The FBI has achieved symbolic victory, but the Anonymous group in its widest sense includes a lot of people, most of who remain unknown," he said.
"We can see that they are threatening more attacks on Fridays and the movement is likely to carry on. But the question is whether any potential leaders - those who help achieve the big hits by dedicating a lot of time and skill - have been scared away."