The head of FEMA’s Urban Search and Rescue branch, which runs a network of teams stationed across the country that can swiftly respond to natural disasters, resigned on Monday.

Ken Pagurek’s departure comes less than three weeks after a delayed FEMA response to catastrophic flooding in central Texas caused by bureaucratic hurdles put in place by the Department of Homeland Security, which oversees the disaster response agency.

Pagurek told colleagues at FEMA that the delay was the tipping point that led to his voluntary departure after months of frustration with the Trump administration’s efforts to dismantle the agency, according to two sources familiar with his thinking. It took more than 72 hours after the flooding for Homeland Security Secretary Kristi Noem to authorize the deployment of FEMA’s search and rescue network.