How did the fugitive slave act cause tension between the north and south?

The Fugitive Slave Act required the return of escaped slaves to their owners, increasing tensions as many in the North opposed the practice of slavery. It also empowered slave catchers to capture fugitive slaves in free states, leading to backlash from abolitionists and free-state residents who resisted enforcement of the law. This deepened the divide between the North and South over the issue of slavery and states' rights.