The infected running and chasing after Aziel weren't as agile and dexterous as him, as they stepped over their dead brethren as well as tried to navigate through the sticky, gooey layer of pool of blood around them began to slip and fall over.
Due to the narrow passageways, the horde was rather disorganized, and whilst there were potential fast runners in the midst they couldn't force themselves to the forefront fast enough. As such those at the front that slipped on the floor became the catalyst for the rest of the horde, kicking off the domino effect to happen amongst the rest of them following after. Many of the infected began to fell down and pulled those nearby along with them.
Still, besides their relentless chase hitting a hurdle and being forced to a temporary hold, they weren't hurt either. Maybe a few superficial injuries that meant absolutely nothing to these creatures.