If there is no intravenous access, diazepam 10?20 mg rectally - repeated once 15 minutes later if there is a continued risk of status epilepticus.
or midazolam 10 mg as a buccal preparation.

In those with intravenous access, lorazepam given as an intravenous dose of 0.1 mg/kg (usually a 4 mg bolus, with a further dose after 10?20 minutes) is preferred. Diazepam 5–10 mg administered slowly intravenously is an alternative.