Representative Nancy Pelosi, former House speaker and a key ally of Joe Biden, signed a letter on Friday from dozens of congressional Democrats to the president and Secretary of State Antony Blinken, urging a halt to weapons transfers to Israel, Reuters reports.

Friday’s letter called on the Biden administration to conduct its own probe into an Israeli airstrike that killed seven staff of the aid group World Central Kitchen on Monday.

“In light of the recent strike against aid workers and the ever-worsening humanitarian crisis, we believe it is unjustifiable to approve these weapons transfers,” the letter said. It was signed by Pelosi and 36 other Democrats including Representatives Barbara Lee, Rashida Tlaib and Alexandria Ocasio-Cortez.