U.S. regulators asked Sarepta Therapeutics on Friday to voluntarily halt shipments of its Elevidys gene therapy after a muscular dystrophy patient who received a different, experimental treatment died,

The move follows the death of two teenagers who were administered the treatment, as well as the death of a 51-year-old man who received a similar product in a clinical trial for a different form of muscular dystrophy.

Investors showed growing mistrust of the Sarepta team, repeatedly asking why the Cambridge company had not disclosed the death earlier and whether there have been other unreported fatalities.