A caravan-size influx of migrants is flooding across the border each week in just a single sector, a top Border Patrol official told lawmakers Tuesday -- the latest indicator of the growing migration crisis on the southern border. “Much media attention has focused on caravans coming across from Central America,” Rio Grande Valley Sector Chief Patrol Agent Rodolfo Karisch said at a Senate Homeland Security Committee hearing. “But the fact is that RGV is receiving caravan-equivalent numbers every seven days.” Karisch said his sector has apprehended people from 50 different countries, including China, Bangladesh, Turkey, Egypt and Romania. “People are...