I think at the very least it's going to be a three digit number. It happened late at night so there were less people on the street, but there's a lot of destroyed houses and flying debris to account for.
The Chinese seismology agency has stated that the first explosion was the equivalent of 3 tons of TNT, and the second 21 tons, further smaller blasts were triggered nearby.
http://www.bbc.co.uk/news/world-asia-china-33896292