Rolling brownouts are taking three Houston fire trucks out of service.

The fire chief pulled those units on Friday, after having more than 35 employees called in sick.

Chief Terry Garrison says the brownouts are required when unscheduled absences exceed the daily limit.

A union spokesperson tells Local 2 the fire trucks are second-level response units and no ambulances were taken out of service, but the fire chief said  this isn't the end of the "brownouts."

It looks like over the weekend we'll have some more unit's that we'll have to reduce," said Garrison. "It's my responsibility to make sure we're within budget and implement this reduction plan."

HFD has not said when they plan to put the units back in service.