A freak overnight storm in Chicago Friday caused flooding that stranded two big rig drivers who had to be rescued from their rigs by boat on a southside expressway.

Chicago Fire Department spokesman Larry Langford told the Chicago Tribune that the water was so deep where the Bishop Ford Expressway meets I-57 that the Chicago Fire Department had to use a boat to rescue two truck drivers whose trucks were nearly submerged.

Three semis — two tankers and a van trailer — where up to their mirrors in water, forcing one driver to swim for it and two others to climb onto the tops of their trucks to await rescue by a fire department boat.

The rapid rainfall dumped a record 6.91 in., the largest single-day rainfall since records began in 1871. The highest previous daily total was 6.64 in. on Sept. 12, 2008. And more rain is expected.