JERUSALEM (JTA) — Israel’s public security minister said 40 to 50 percent of the fires that raged across Israel over the past week were caused by arson.

Addressing the Knesset Wednesday, Gilad Erdan said he came to those numbers based on “the estimates of professionals” and “findings on the ground,” according to a transcript of his speech.

“These estimates are based upon facts. When you see two Molotov cocktails with flammable materials, and you see that the fire started from there, you understand that this is arson, and there were a number of cases like this,” he said.

Erdan questioned the Fire Services estimate that firefighters battled 1,773 wildfires in Israel and the West Bank between Nov. 18 and 26, saying that in many cases “20 people called in about the same event, and this was counted,” and that fires from unrelated car crashes were also included.

The Fire Services refused to comment, according to The Times of Israel.

The Israel Police said Tuesday it was too early to know how many of the hundred of fires were the result of arson and terrorism. At the time, police had arrested at least 35 people on suspicion of arson or incitement to arson.