LOS ANGELES—A smoky wildfire churning through a Los Angeles canyon community gained strength Sunday as about a thousand residents remained under evacuation orders while others were warned they should get ready to leave, authorities said. The cause of the fire near Topanga State Park has been deemed “suspicious” and is under investigation, the Los Angeles Fire Department said. Arson investigators with the fire department and the Los Angeles Police Department identified one individual who was detained and released. Investigators then detained a second suspect and were questioning them Sunday evening, according to a statement from fire department spokesperson Margaret Stewart. Cool, moist weather early in the day gave firefighters a break, but by afternoon flames starting moving again in steep terrain where tinder-dry vegetation hasn’t burned in a half-century, the fire department said. “We’re definitely seeing increased fire activity,” said Stewart. No structures were damaged and no injuries were reported …