A top Environmental Protection Agency official came under heavy fire Tuesday when Republicans at a congressional hearing accused the agency of failing to protect Flint, Michigan from their water being poisoned by lead.

"You screwed up and you ruined people's lives," Rep. Jason Chaffetz, R-Utah told Susan Hedman – the top EPA official in the region, who resigned as the crisis worsened. Hedman had been accused of downplaying the warnings of EPA scientists about lead poisoning in the area..

The most shocking moment of the hearing came when Chaffetz produced a memo between officials, in which one employee wrote "Perhaps she already knows all this but I'm not so sure Flint is the community we want to go out on a limb for." The memo produced audible gasps from the hearing hall.

Professor Marc Edwards of Virginia Tech, who helped to expose the lead problem in Flint’s water, said Hedman and the EPA were unremorseful for their actions and accused them of “willful blindness.”

Flint switched its water source from Detroit's water system to the Flint River in 2014 to save money, but the river water was not treated properly and lead from aging pipes leached into Flint homes and businesses. Elevated levels of lead have been found in children's blood. Lead contamination has been linked to learning disabilities and other problems.

The chain of events has spurred calls for Republican Gov. Rick Snyder to resign, including from Bernie Sanders and Hillary Clinton. Synder is currently facing a possible recall effort in Michigan. But the EPA has also faced significant criticism for allegedly knowing about the high lead levels in 2015, but not taking action until this year.

Hedman said she resigned due to “false allegations” that she sat on the sidelines after finding out Flint was not implementing corrosion controls in June, and that she muted concerns of an EPA scientist about lead in the water.

“That’s completely untrue,” she said. “I did not sit on the sidelines and I did not downplay any concerns raised by EPA scientists or apologize for any memos they wrote

In her testimony, Hedman defended herself and the EPA, saying "I don't believe anyone at the EPA did anything wrong, but I believe we could have done more."

Choking up at one point, she said she has not stopped thinking about the people of Flint since she resigned.

“What happened in Flint, should not have happened anywhere in United States – and I was horrified that it happened in my region, the Great Lakes Region. I thought – and still think – that resigning was the honorable thing to do,” she said.

However, Chaffetz was not sympathetic.

“You still don't get it. You screwed up. And you messed up people's lives,” he told Hedman.

Rep. Elijah Cummings, D-Md. – the top Democrat on the committee, agreed the EPA should have done more, but also blamed state authorities in Michigan for failing to act.

The Associated Press contributed to this report.