Kansas City, which also got a homer and two RBIs from Kila Ka'aihue, rallied from a 3-0 deficit to snap Detroit's five-game winning streak and avoided being swept in the three-game series.
Phillip Humber (1-0), who pitched three innings of scoreless relief, got the win for the Royals and Joakim Soria got his 36th save in 38 chances.
Alfredo Figaro (0-1) surrendered Bloomquist's home run and took the loss.
Ka'aihue's homer off Detroit starter Armando Galarraga leading off the seventh made it 3-1. It was the second straight game that Kai'aihue has homered.
Ryan Perry allowed Mike Aviles' leadoff single in the eighth before getting the next two batters. Tigers' closer Jose Valverde replaced Perry and, after Aviles stole second, gave up Ka'aihue's run-scoring double into the right-field corner. Brayan Pena followed with a double over Austin Jackson's head to tie the game at 3.
Valverde's streak of 24 consecutive save opportunities converted was snapped.
Detroit took a 3-0 lead in the second inning. Santiago's two-run triple with one out scored Brennan Boesch and Ryan Raburn. Boesch led off with a double and Raburn singled. Santiago scored when Gerald Laird followed with a RBI double.
Galarraga allowed a run on five hits in 6 1-3 innings, walking two and striking out four.
Royals' starter Sean O'Sullivan gave up three runs on seven hits in seven innings. He didn't walk a batter and struck out one.
Notes: Detroit's Jackson led off the game with an infield single. It was the sixth consecutive contest he reached base leading off a game. ... Ka'aihue made a nice backhand stab to his right at first on Ryan Raburn's low one-hop liner with two out in the bottom of the eighth with the score tied 3-3 and Miguel Cabrera on second base. ... Cabrera made a diving stab to his left at first on a liner by Jai Miller, who led off the top of the ninth.