My family flew across the country from a family member's wedding yesterday. while we were flying above utah, around 40,000 to 50,000 ft in altitude, we saw a white oval-shaped craft flying in the opposing direction of the plane. it was traveling at the same altitude and was moving rather fast. it was also emitting red/purplish fumes from its rear, something i have never seen before. it was very surprising. i took my phone out to take a video but did not do this in time. this occurred around 4:05 ndt. we also saw two jets traveling in the same direction of the craft later on at high speeds. we saw the first jet around 4:12 ndt and the second around 4:54 ndt. this specifically occurred as the commercial flight was above central/southwest utah. in regards to the craft, it was extremely close to the plane, which is surprising as known flying vehicles would never be allowed to be that close to a commercial airplane. the shape and appearance of the craft differed entirely from anything i have seen before. it was a white pill-shaped craft with no noticeable wings, exhausts, or external features that i could see. as far as size, i am uncertain. obviously it looked pretty small from the window of the airplane as my eyes perceived it. i think it was a pretty big craft though because the jets that followed were of similar size from the perspective of the plane. this was a very shocking event for both my mother and i, who observed the craft and the subsequent jets. i will be reporting this event to as many organizations and entities as possible. thank you.