A group of Senate Democrats led by Minority Leader Chuck Schumer ordered United Airlines to “make necessary improvements” to their overbooking policy after a passenger was dragged off an airplane to make room for airline staff.

In a letter to United CEO Oscar Munoz, Schumer, D-N.Y., Minority Whip Dick Durbin, D-Ill., and 19 other Democrats also demanded United provide more information about their overbooking policy as well Sunday’s incident, in which police dragged a bloodied passenger down the airplane aisle and were captured on video.