Another suspicious fire sent crews racing to a Renton high school early Wednesday morning. Firefighters have put out several blazes around Lindbergh High School this month - and they all sound suspicious. Crews also had to respond to at least one fire at nearby Tiffany Elementary School earlier this month. The latest fire was discovered just after 1 a.m. Wednesday when 911 dispatchers got a call about a mattress on fire near the football fields at Lindbergh High School. Crews extinguished that fire and also learned a large trash bin was on fire at the other end of the school. Nothing else was damaged - and school is out for the summer so this won't impact any classes. The mattress fire is just a few feet from where a portable potty was apparently set on fire just last week. That same night, another portable potty burned at Tiffany Park Elementary School just a few blocks away. The disturbing trend may go back several months - in January a van was set on fire at Lindbergh High.