Reference for Yoma 43:5

והרי איברים ופדרים דעבודת לילה היא ותקינו לה רבנן פייסא סוף עבודה דיממא היא

ONE OF THEM PUSHED HIS FELLOW WHO FELL AND BROKE HIS LEG. WHEN THE COURT SAW THAT THEY INCURRED DANGER, THEY ORDAINED THAT THE ALTAR BE CLEARED ONLY BY COUNT. THERE WERE FOUR COUNTS.

Jastrow