The Food and Drug Administration will step up its crackdown on e-cigarette sales to teens, the head of the agency said Tuesday.

Lawmakers on a House Appropriations subcommittee grilled FDA Commissioner Scott Gottlieb about excessive use of e-cigarettes among youths. The FDA has the authority to go after e-cigarette makers and retailers if they violate a ban on sales to people under 18, but lawmakers questioned if the agency was doing enough.