Rescue crews from several countries were searching Saturday afternoon for the missing Malaysian Airlines jetliner as the airline asked for prayers from around the world for Flight 370. In a statement early Sunday local time — and more than 24 hours after air traffic controllers lost touch with the jumbo jet flying from Kuala Lumpur to Beijing— the airline said there was still no evidence of wreckage. In a possible clue, Vietnamese air force planes spotted oil slicks off the coast of Vietnam. The airline said it was sending “caregivers and volunteers” to Beijing, where anguished family members have been waiting for news. The plane, carrying 239 people, including three Americans, last made contact with air traffic control over the water between Malaysia and Vietnam and then disappeared without sending a distress signal. Of the 239 people on board, 227 were passengers — 152 of them Chinese — and 12 crew members. One of the three Americans on board was an infant.