After Rio museum fire, questions about cause, what survived

The National Museum, seen from above, stands gutted after an overnight fire in Rio de Janeiro, Brazil, Monday, Sept. 3, 2018. A huge fire engulfed Brazil's 200-year-old museum, lighting up the night sky with towering flames as firefighters and museum workers raced to save historical relics from the blaze. (AP Photo/Mario Lobao)
photo Students and National Museum employees protest outside the institution after it was gutted by an overnight fire in Rio de Janeiro, Brazil, Monday, Sept. 3, 2018. Recriminations flew over who was responsible for the loss of at least part of Latin America's largest archive of historical artifacts, objects and documents. (AP Photo/Silvia Izquierdo)

RIO DE JANEIRO (AP) - Forensic investigators and researchers awaited access Tuesday to the National Museum of Rio de Janeiro, gutted in a fire, to find out how the blaze began and what remains of the 20 million artifacts that made the museum one of the most important in Latin America.

After a fire tore through the museum Sunday, engineers were doing tests on the structure to make sure it wouldn't collapse.