(CNN) -- U.S. Secretary of Homeland Security Janet Napolitano toured Joplin, Missouri, Thursday and pledged to help residents rebuild the tornado-ravaged city.
"We will not leave until the job is finished," she said in a statement, "and we will continue to support our team of federal, state, local and community partners that are working tirelessly to help the people of Missouri rebuild their communities."
Napolitano toured the areas damaged by the May 22 tornado with Gov. Jay Nixon and Rep. Billy Long. She also met with hospital leadership working in the temporary medical facility set up at St. John's Mercy Hospital.
The secretary also met with state and local leaders and other government officials to discuss plans for recovery efforts.
FEMA has approved $20 million to assist families and individuals, according to a statement released by the U.S. Department of Homeland Security.
Authorities are still assessing damage from the tornado, which left much of the city of splinters. Last month the Eqecat catastrophe risk modeling firm estimated the disaster caused up to $3 billion in damage to the city of about 50,000 people.
At least 151 people were killed in the storm, Assistant City Manager Sam Anselm said Thursday. That makes it one of the deadliest twisters since modern record keeping began in 1950.
Napolitano says the Obama administration remains dedicated to helping Joplin and other Missouri communities hit by the storm.
Napolitano isn't the only federal official to visit Joplin after the tornado; President Barack Obama and FEMA Administrator Craig Fugate also visited the city the day after the tornado hit.
CNN's Molly Green contributed to this report.