The system was set to pay out the weekly requests Friday. Pension officials said allowing the withdrawals would leave them without the liquid reserves required to sustain the $2.1 billion fund.

"Our situation is currently critical, and we took action," board chairman Sam Friar said.

Pension officials and many police and firefighters have blamed Dallas Mayor Mike Rawlings for forcing the latest run on the bank. Dozens of retirees rushed to request withdrawals after Rawlings filed a lawsuit Monday to stop the withdrawals.

By then, more than $500 million had already gushed from the fund since the board proposed benefit cuts in August.