Former Speaker Nancy Pelosi (D-Calif.) and more than 30 House Democrats sent a letter to President Biden and Secretary of State Antony Blinken urging them to reconsider the recent authorization of weapons to Israel, just days after seven aid workers were killed.

“In light of this incident, we strongly urge you to reconsider your recent decision to authorize the transfer of a new arms package to Israel, and to withhold this and any future offensive arms transfers until a full investigation into the airstrike is completed,” the letter said, obtained and first reported by NBC News.

On Monday, seven World Central Kitchen food aid workers were killed by an Israeli airstrike, sparking international outrage and concern among top U.S. officials.

“We also urge you to withhold these transfers if Israel fails to sufficiently mitigate harm to innocent civilians in Gaza, including aid workers, and if it fails to facilitate – or arbitrarily denies or restricts – the transport and delivery of humanitarian aid into Gaza,” the lawmakers wrote.

The letter, signed by more than three dozen Democratic lawmakers, asked the Biden administration to withhold transfers of arms to Israel as an investigation into the airstrike occurs.

Israel acknowledged its misstep in killing the seven workers and said it was unintentional. The lawmakers said it is a “shockingly unacceptable mistake.”

A preliminary investigation carried out by the Israeli Joint Chiefs of Staff found that the military mistakenly thought the workers were armed Hamas fighters. On Thursday, Israel announced it would be opening a border crossing in northern Gaza.

Blinken said Friday that the steps taken by Israel are “positive developments,” but the U.S. will wait and see what Israel does in the coming days and months. President Biden spoke with Prime Minister Benjamin Netanyahu Thursday, where he said U.S. policy in Gaza is dependent on Israel’s immediate next steps.

“While we appreciate your administration’s recent efforts to increase the delivery of desperately needed humanitarian aid to Gaza, these efforts will not be sufficient to meet the extraordinary need on the ground,” the letter said.

A spokesperson for Pelosi said she joined the letter because she is in support of an independent investigation into the aid workers’ deaths. 

“Speaker Pelosi is sympathetic to some of the thoughts in the letter, and she feels very strongly that there must be a comprehensive, independent investigation into the horrific killing of the World Central Kitchen heroes,” Aaron Bennett, a spokesperson for Pelosi, said in a statement. “Speaker Pelosi knows President Biden’s support for Israel and empathy with the innocent civilians in Gaza, and she respects his judgment in how to proceed.”