The tornado that struck on the grounds of Denver International Airport (DIA) on Tuesday, June 18, 2013 has been rated an EF1 with winds up to 109 mph.  The twister came within a half mile of Concourses A and B and sent workers and travelers scrambling to tornado shelters.

Scroll down to see more photos of the tornado.

From the National Weather Service:

A tornado developed on Denver International Airport (DIA) grounds on the afternoon of June 18, 2013. The tornado formed around 2:19 PM just north of 70th Avenue. The tornado then moved slowly northwest between Runway 35R and 35L, and moved to within a half mile of Concourses A and B before dissipating at 2:36 PM. The tornado moved extremely close if not over the ASOS (Automated Surface Observation System) and another low level wind shear sensor at DIA. The ASOS weather observing system reported a 97 mph wind gust at 2:27 PM, while the wind shear sensor reported a wind gust to 109 mph at the same time – indicative of an EF1 tornado. There was only minor damage noted to this equipment. The storm responsible for this tornado first developed just south of the airport, and then drift slowly northward across the eastern side of DIA. At 2:05 PM, there was weak rotation beginning to develop underneath this storm as noted by the velocity data below. This rotation then strengthened quickly between 2:10 and 2:22 PM.