It is believed that debris led to the two tyre failures at the Azerbaijan Grand Prix on Sunday, but Pirelli will not make a definitive statement until its Milan base has conducted an investigation.
Lance Stroll and Max Verstappen walked away from separate 200mph accidents resulting from left rear tyre failures on their cars.
In the wake of Verstappen's accident, the race was red flagged with two laps remaining, allowing Sergio Perez to win in a sprint to the finish line.
There was some confusion over the cause of these two accidents, but a cut located on Lewis Hamilton's left rear tyre might offer some insight.
Hamilton's tyre cut was not deep enough to result in a failure, but adds to the speculation that debris somewhere on the track damaged the tyres of Verstappen and Stroll.
Additionally, Pirelli excluded the possibility that the tyre failed due to excessive wear because neither of the tires on the affected vehicles displayed an unusually low tread depth at the spot where each tyre failed.
Pirelli Head of F1 and Motorsport, Mario Isola, issued the following statement:
"I believe I can exclude that failures were due to tyre wear, because it is not a matter of tyre wear.
"We found a cut on the inside shoulder of the rear left tyre used by Hamilton in the same stint.
"The cut was quite deep and big -- probably 6-7 cm -- but not cutting the construction, so the tyre was still in one piece.
"Just the tread is cut [on Hamilton's tyre], and when there was the red flag and Lewis came to the pit lane and changed the tyres we were able to find the cut.
"The left rear is not the most stressed in Baku, as talking about the tyres it is obviously rear right [that is most stressed].
"This is the preliminary investigation.
"There was no sign, or any warning, according to the teams. We have to receive the telemetry from them, but they told me there was no warning, no vibration, nothing to think there could be something in the tyres.
"Consider that the tyres fitted on the cars that crashed were back in the garage and in our fitting area just minutes ago, we need a bit of time to analyse them -- I don't want to give any preliminary conclusion.
"But it seems it is a cut due to debris. It is not a more-stressed tyre and we have evidence of another cut in the same position [on Hamilton's tyre].
"Both the accidents happened on more or less the same part of the circuit and a few laps difference, so we have other cars with the same number of laps, same tyres, without any issues.
"So the preliminary investigation is that it is probably due to an external factor or debris, kerb, or whatever, but I don't want to jump to a conclusion now as the plan now is to make a thorough investigation and make a report to the teams and the FIA that will be hopefully before Paul Ricard.
"Obviously it is a priority."