Śrīmad-Bhāgavatam · Text 10.11.4
Who is speaking and story frame
बाला ऊचुरनेनेति तिर्यग्गतमुलूखलम् ।
विकर्षता मध्यगेन पुरुषावप्यचक्ष्महि ॥ ४ ॥
bālā ūcur aneneti
tiryag-gatam ulūkhalam
vikarṣatā madhya-gena
puruṣāv apy acakṣmahi
Then all the cowherd boys said: It is Kṛṣṇa who has done this. When He was in between the two trees, the mortar fell crosswise. Kṛṣṇa dragged the mortar, and the two trees fell down. After that, two beautiful men came out of the trees. We have seen this with our own eyes.
Read Śrīla Prabhupāda's purport on Vedabase.io