(AP) — Last year’s tornado season wasn’t the worst in Oklahoma history, either in the number of twisters or the number of lives taken.

But the deadly barrage that killed more than 30 people scared Oklahomans in a way that previous storms had not, moving them to add tornado shelters or reinforced safe rooms to their homes.

There’s just one problem: The surge of interest in tornado safety has overwhelmed companies that build the shelters. Now there are long waiting lists, and many people have to endure the most dangerous part of the season with no added protection.

In 2009, just 322 permits shelter permits were issued in Oklahoma City. Since May 2013, that number has risen to more than 8,000.

Workers at Norman-based Thunderground Storm Shelters are booked solid until mid-June.