The bridge over the Shellpot Creek was the only way in and out of the complex that's home to La Casa, Ridge, and the Colony North apartments.
It could take several weeks, even months, to fix the bridge.
So, county officials are creating a temporary road through other private property.
"This is terrible. My mom can't get to work, she might lose her job over this. This crazy," said resident Christina Robinson.
Delaware Department of Transportation spokesman Mike Williams says the bridge is privately owned and not maintained or inspected by the state.
Meanwhile, flooding has caused the partial collapse of a town home in Newark, Delaware.
It happened Friday morning on Woodmill Court in the Woodmill Townhome community.
The basement wall of one of the townhomes has collapsed and there are fears several others may be affected.
License and Inspection is accessing the damage.
Delaware Gov. Jack Markell has declared a limited state of emergency.
There were no reports of any injuries in Delaware.