HARRISBURG — More than two dozen gun dealers and a state lawmaker filed a lawsuit Friday seeking to block a planned four-day freeze on gun sales to allow an upgrade of the state's computerized background check system.

The gun shops and Rep. Timothy Solobay, D-Washington, say the system upgrade could be completed without shutting down the system or by performing the work after normal business hours.

C. Robert Keenan III, a Pittsburgh lawyer representing the gun dealers in the Commonwealth Court suit, said state police also could use a national system of computerized background checks as an alternative.

"If it has to be shut down during the day, have the (state police) personnel connect to the national instant check system and get it done that way," Keenan said.

Gun dealers have complained that they received insufficient notice from state police about the planned Sept. 2-6 interruption in sales, which falls during the first few days of dove and Canada geese hunting season.

Gov. Ed Rendell said Thursday he would appoint an informal panel that will meet with state police officials and decide by early next week whether the computer work can be done later this fall. If that is feasible, he said he would order that the work be postponed; if not, he said the current schedule will stand.

The same system also is used to investigate the backgrounds of teachers and other people entrusted with the care of children.

George Romanoff, owner and president of Ace Sporting Goods, one of the dealers represented by Keenan, said the shutdown would cause a hardship for customers who drive from as far as 50 miles away to purchase firearms at his store.