The martyrdom of Karuṇāśrīmitra
Roughly one thousand years ago a roughly similar sight greeted a marauding army from Bengal. For reasons best known to themselves they came here - the great monastery of Somapura - to set it on fire. We know of this because four academic generations later a monk called Vipulaśrīmitra commissioned an inscription describing how the fountainhead of his lineage met his end in this sad event.
"For example, we find construction in honor of the martyrdom of the eminent monk Karuṇāśrīmitra, who went to the Buddha's heaven after having been burned to death by a Baṅgāla army while he was trying to save his monastery of Somapura. A disciple in his line constructed statues and monasteries in several locales around North India, including a monastery specifically dedicated to his Vinaya lineage, the Mitras. The interesting part, though, is the inscription celebrating this in the proximity of the Nālandā grounds, where it was set up so that its message might gain greater response and achieve the public appreciation that was its due."Ronald Davidson, Indian Esoteric Buddhism (p. 110)
There are several problems with these statements. It seems that the inscription was not commissioned to commemorate Karuṇāśrīmitra's martyrdom, but rather the collective achievements of Vipulaśrīmitra himself and possibly his masters beginning with Karuṇāśrīmitra. That an army should burn monks is not unusual, attrocities are committed everywhere and against everyone. But here it seems that Karuṇāśrīmitra simply refused to leave the hall which was burning around him. Instead he clutched the feet of the Buddha (most likely an image) and died, presumably consumed by the fire. He did not go to "the Buddha's heaven", this somewhat odd collocation is the result of miscontruing a genitive. The text simply says in a polite manner that 'he died', lit. 'went to heaven'. Whether he was trying to save the monastery or not is unclear. I do not see any strong evidence for this in the verse. There are more problems with the paragraph, but I'll leave it here for the moment. Instead, here is the stanza in question:
śrīmatSomapure babhūva Karuṇāśrīmitranāmā yatiḥ
kāruṇyād guṇasaṃpado hitasukhādhānād api prāṇināṃ[|]
yo Vaṅgālabalair upetya dahanakṣepāj jvalaty ālaye
saṃlagnaś caraṇāravindayugale Buddhasya yāto divam|| 
"There was in majestic Somapura an ascetic/a devotee called Karuṇāśrīmitra, who - because of his compassion, abundance of virtues, as well as his dedication to act for the welfare and happiness of beings - when the armies of Bengal arrived and started a conflagration, passed away in a burning hall clutching the lotus-feet of the Buddha."
UPDATE: for a high-resolution b/w image of the inscription click here.