ADEN—At least 20 people were killed and dozens wounded in an attack on Yemen’s Aden airport on Wednesday moments after a plane landed carrying a newly formed Saudi-backed cabinet for government-held parts of Yemen. Hours after the attack, a second explosion was heard around Aden’s Maasheq presidential palace where the cabinet members including Prime Minister Maeen Abdulmalik, as well as the Saudi ambassador to Yemen, had been taken to safely, residents and local media said. In the airport attack, loud blasts and gunfire were heard shortly after the plane arrived from Riyadh, witnesses said. A local security source said three mortar shells had landed on the airport’s hall. Aden health official Mohamed Robeid gave the death figure and said 50 people were wounded, adding the death toll could rise. Medecins Sans Frontieres aid group earlier said 17 people had been treated for wounds at its hospital in Aden. There was …