A.T. Robertson Commentary Revelation 8:7

"And the first sounded, and there followed hail and fire, mingled with blood, and they were cast upon the earth: and the third part of the earth was burnt up, and the third part of the trees was burnt up, and all green grass was burnt up." — Revelation 8:7 (ASV)

Sounded (εσαλπισεν). First aorist active indicative of σαλπιζω, repeated with each angel in turn (8:8,10,12; 9:1,13; 11:15).

Hail and fire mingled with blood (χαλαζα κα πυρ μεμιγμενα εν αιματ). Like the plague of hail and fire in Ex 9:24. The first four trumpets are very much like the plagues in Egypt, this one like a semitropical thunderstorm (Swete) with blood like the first plague (Exodus 7:17ff.; Psalms 106:35). The old feminine word χαλαζα (hail) is from the verb χαλαω, to let down , in N.T. only in Re 8:7; 11:19; 16:21. The perfect passive participle μεμιγμενα (from μιγνυμ, to mix) is neuter plural because of πυρ (fire).

Were cast (εβληθη). First aorist passive singular because χαλαζα and πυρ treated as neuter plural. "The storm flung itself on the earth" (Swete).

Was burnt up (κατεκαη). Second aorist (effective) passive indicative of κατακαιω, old verb to burn down (effective use of κατα, up, we say). Repeated here three times for dramatic effect. See 7:1-3 about the trees and 9:4 where the locusts are forbidden to injure the grass.