Update: In a statement, TSMC said the virus incident would reduce estimated third quarter revenues by 3%, as well as shipment delays that would be caught up by the fourth quarter.

According to a report from Bloomberg, Apple supplier TSMC was forced to shut down several of its factories late last night due to a “computer virus.” While details are unclear at this point, the shutdown comes as TSMC is ramping up chip production for the new iPhone models coming this year…

In a statement, TSMC explained that “a number of its fabrication tools had been infected.” While the problem has been contained and “some production has resumed,” several of the company’s factories won’t begin production again until Sunday at the earliest.

The extent of the infiltration varies on a factory by factory basis, TSMC added. The chipmaker does not believe the virus was introduced by a hacker, but it’s unclear who is responsible at this point.

In a statement to Bloomberg, TSMC chief financial officer Lora Ho said that this is not the first time the company has been hit by a virus attack, but it is the first time such an attack has taken production lines down:

The CFO, however, wouldn’t elaborate on the specific effects of the downtime, including whether or not iPhone production specifically has been affected and the effects on revenue.

“Certain factories returned to normal in a short period of time, and we expect the others will return to normal in one day,” the company said in its Saturday statement.

Back in May, it was reported that TSMC had started mass production of the 7-nanometer A12 processors seemingly destined for this year’s iPhone models. The company continues to ramp production of the new chip as we inch closer to this year’s release.