In their final debate before the Iowa caucuses, the gloves came off between Hillary Clinton and Bernie Sanders.

Hillary Clinton and Senator Bernie Sanders in the Democratic Candidates Debate hosted by NBC News and YouTube in Charleston, South Carolina. (Photo by Andrew Burton/Getty Images)

Shouting over each other at times, the two engaged in some of their toughest exchanges of the campaign, underscoring the narrowing race in Iowa and New Hampshire.

Clinton sought an advantage over Sanders on curbing gun violence.

Sanders, meanwhile, twice assailed the former secretary of state for accepting big money in speaking fees from Wall Street, drawing some boos as he did so.

Health care emerged as a major dividing line.

Sanders released a proposal that would create a "Medicare for all" health care system funded by higher taxes on middle class families and the wealthy.