It wasn't immediately clear who fired the shells but Islamic militants in Egypt's lawless Sinai have been behind a number of such attacks in recent years.
Jim Mattis is likely to face questions about Donald Trump's remarks that America should have seized Iraq's oil after toppling leader Saddam Hussein.
Philippine President Rodrigo Duterte has repeatedly denied involvement in vigilantism or summary executions.
Iraqi forces fought IS fighters to clear the way to Mosul's airport, on the second day of a ground offensive on the jihadists' remaining stronghold in the western side.
Former policeman Arthur Lascanas' lawyers said the allegations could be grounds for impeaching President Rodrigo Duterte.
Islamist groups have held two big rallies since November against Governor Basuki Tjahaja Purnama, who is on trial for insulting the Koran.
The bus lost its brakes on a downhill road and slammed into a post in the hilly town of Tanay in Rizal province east of Manila.
Critics said the changes approved could turn Cambodia into a de facto one-party state.
Netanyahu again raised the possibility of a 'regional approach' to Israeli-Palestinian peace on Wednesday.
Planning for 'the talks' is still in a preparatory stage, The Washington Post reported on Sunday.