Brock Long, head of Federal Emergency Management Agency, announces he's leaving the agency

Brock Long, the head of the Federal Emergency Management Agency who oversaw the U.S. response to some of the most devastating hurricanes and wildfires in history, announced Thursday he is leaving the agency to spend more time with his family.

Long was chosen by President Donald Trump to lead FEMA and was confirmed by the Senate in 2017. Since then, he oversaw the federal response to more than 220 declared disasters, including six major hurricanes and five wildfires.

Among the biggest storms under Long's watch was Hurricane Maria in Puerto Rico. The 2017 storm caused some $140 billion in economic damage, and according to one independent study, was tied to the deaths of some 2,975 people.

In its own after-action report, FEMA’s leadership acknowledged it "could have better anticipated that the severity of hurricanes Irma and Maria would cause long-term, significant damage" to Puerto Rico and the U.S. Virgin Islands.

"While this has been the opportunity of the lifetime, it is time for me to go home to my family -- my beautiful wife and two incredible boys," Long said in a statement.

Last fall, an internal investigation concluded that Long improperly used government resources to commute to his home in Hickory, North Carolina. At the time, Long said any wrongdoing was unintentional and that "doing something unethical is not part of my DNA."

The Department of Homeland Security inspector general found that Long’s unauthorized use of transportation cost the government $94,000 in staff salaries, $55,000 in travel expenses and about $2,000 in operations and maintenance.

Homeland Security Secretary Kirstjen Nielsen acknowledged that the use of government vehicles was "established practice" by other FEMA administrators. But because Long’s commute home was several hours away, he promised to reimburse the government for use of the vehicles.

In a statement released Wednesday, Nielsen said Long "has admirably led the men and women of FEMA during very difficult, historic and complex times."

Deputy Administrator Pete Gaynor was expected to become acting administrator.