Semien’s two-run homer struck high up the left-field foul pole to break a 1-1 tie. Seager followed with a shot to right field on the next pitch.
Shohei Ohtani hit a two-run homer in the ninth, his AL-leading 21st. It extended his hitting streak to a season-high 11 games.
Leody Taveras hit a solo homer in the third and added one of two RBI singles in the eighth inning.
The Angels saw a three-game winning streak end as they left 10 runners on, nine in the first four innings.
Josh Sborz (3-2) got the win working scoreless seventh and eighth innings.
Jimmy Herget (1-3) allowed Texas’ three seventh-inning runs in his one inning of relief of Reid Detmers.
The Angels scored their run when Mike Trout drew a two-out walk and came around on Anthony Rendon’s flare that struck the inside of the right-field line about 200 feet from home plate. Texas right-fielder Adolis Garcia, who leads major league outfielders with nine assists, rifled a throw to the plate just as Trout rounded third. The throw landed in front of the plate and bounced high over catcher Mitch Garver as Trout slid in.