DEIR AL-BALAH, Gaza Strip — Deadly airstrikes in Gaza on Wednesday cast more doubt on whether new U.S. efforts can advance a tenuous ceasefire in the Palestinian territory.

Just two days after U.S. negotiators reportedly asked Israel to draw down attacks in the Gaza Strip , at least 10 people were killed Wednesday in two strikes, according to local hospitals and the Palestinian Red Crescent. Israeli troops also crossed the ceasefire line in southern Gaza and detained a Hamas police colonel at dawn Wednesday, two witnesses and a Hamas official said.