WASHINGTON (AP) — Republican lawmakers are criticizing the government response to the arrival of Ebola on U.S. shores.

The criticism came at a House hearing where top public health officials have been defending their actions.

Republican Fred Upton of Michigan, who chairs the Energy and Commerce Committee, said Americans are “scared.” He said, “People’s lives are at stake, and the response so far has been unacceptable.”

Dr. Thomas Frieden, who heads the Centers for Disease Control and Prevention, said he remains confident in the ability of the U.S. health care system to fight Ebola.

But he also raised alarms of his own about threats to the U.S. if the raging epidemic in West Africa can’t be stopped. It has already claimed more than 4,000 lives.

Frieden said, “To protect the United States we need to stop it at its source.” He says if it spreads more widely in Africa, it could become a long-term threat to the U.S. health system.

Several lawmakers at today’s hearing suggested a partial travel ban for people who have been in West Africa.

Copyright 2014 The Associated Press.