Majority Leader Harry ReidHarry Mason ReidDems walk tightrope on Pompeo nomination The Memo: Teens rankle the right with gun activism Dems to party: Go on offense with Trump’s alleged affairs MORE (D-Nev.) called the bombings a “senseless” act of violence that killed at least three people and injured many more.

“Americans are still reeling from the senseless violence at the Boston Marathon yesterday,” Reid said. "Our nation is united in its sympathy for the victims of the attack and their families."

McConnell said the event reminded the public of the “hatred and contempt” some have against America.

McConnell recognized the first-responders and victims, including an 8-year-old boy who died. McConnell said the boy was at the marathon cheering on his father near the finish line, where the first bomb went off.

“In moments like this we see the worst of humanity — and the best of our fellow citizens,” McConnell said. “Whether it was the exhausted marathoners who became helpers and healers the moment they realized what had happened; the doctors and nurses who had expected the usual Marathon-day uptick in cases of dehydration or exhaustion, but who spent the rest of their day handling far worse; or the first-responders and law enforcement officials who rushed to the scene with total disregard for their own safety. … We honor all of them today.”

Little is known about who executed the attack Monday, but McConnell and Reid reiterated President Obama’s vow to bring the perpetrators to justice.