FED overtime ules question

[jTheUmp]

From the overtime procedures section:

If the defensive team gains possession, the ball becomes dead immediately and the offensive series of downs is ended.

Ok, so no pick-six or fumble return for TD or blocked FG returned for a TD or anything like that. Got it.

But then, a bit later, there's this nugget:

If a safety is scored by the offensive team, the succeeding spot will be the 10-yard line of the team that was on defense, provided that the defensive team has not had its series of downs (temporary overtime score is: Team A 2, Team B 0).

My question:
Under what possible circumstance can Team A score a safety in overtime? The down ends as soon as Team B gains possession of the ball, and Team A cannot score a safety unless Team B is in possession of the ball. What am I missing?