Thousands of people were under orders to evacuate broad areas of Northern California Wednesday as some 30 wildfires blazed across the state amid a blistering heat wave now in its second week. “Throughout the state of California right now, we are stretched thin for crews” because of the fires, said Will Powers, a state fire spokesman. At least seven fires were grouped together as one of two major Lightning Fires in Northern California, a nod to their origins just a day earlier.